A Republican lawmaker questioned President Obama's birthplace on Tuesday, joining the ranks of conservative "birthers" who have raised doubts about the validity of the president's birth certificate.

During an appearance on Michael Patrick Shiels' radio show, Michigan state Sen. Tom Casperson (R-Escanaba) was asked if he believed that the president was born in the United States.

"Don't know," Casperson replied, in a clip recorded by progressive watchdog group Progress Michigan.

Casperson said that he thought it was "strange" that the mainstream media has not explored the issue.

"Based on everything everybody's saying, I don't know because it seems like that issue was dropped immediately as far as major media went," he said. "My gut tells me if had been a different president, like say George W. Bush, they'd have been digging into that like there was no tomorrow and trying to get to the bottom of it, which they really never did try to get to the bottom of, so it became a conspiracy theory and no big deal."

He continued, "I think it's strange, again, that it's not being looked at by certain groups that normally would."

Although the president was born in Hawaii, his birthplace has long been a topic of debate among some conservative conspiracy theorists. In 2011, the White House responded by releasing Obama's long-form birth certificate, but the move did little to quiet the most fervent birthers.

Earlier this year, former Secretary of State Colin Powell blasted the movement and advised Republicans to reject birther arguments.

“Republicans have to stop buying into things that demonize the president," Powell said on ABC News. "I mean, why aren’t Republican leaders shouting out about all this birther nonsense and all these other things? They should speak out."

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  • The American Conservative Union's 2012 Rankings

    On Feb. 21, 2013, <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">The American Conservative Union</a> released its 2012 conservative ratings guide. Which members of Congress had a perfect score?

  • Sen. Ron Johnson (R-Wis.)

    (Photo By Bill Clark/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Sen. Jon Kyl (R-Ariz.)

    (Photo By Tom Williams/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Sen. Mike Lee (R-Utah)

    (Photo by Chip Somodevilla/Getty Images) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Sen. Mitch McConnell (R-Ky.)

    Andrew Harrer/Bloomberg via Getty Images <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Sen. Rand Paul (R-Ky.)

    (Photo by Brendan Hoffman/Getty Images) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Sen. Marco Rubio (R-Fla.)

    (SAUL LOEB/AFP/Getty Images) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Sen. Pat Toomey (R-Pa.)

    (Photo By Bill Clark/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Michele Bachmann (R-Minn.)

    (MANDEL NGAN/AFP/GettyImages) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Diane Black (R-Tenn.)

    (Photo By Tom Williams/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Marsha Blackburn (R-Tenn.)

    (Photo by Mark Wilson/Getty Images) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Paul Broun (R-Ga.)

    (Photo By Douglas Graham/Roll Call/Getty Images) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Dan Burton (R-Ind.)

    (Photo by Alex Wong/Getty Images) <em><a href="http://www.huffingtonpost.com/2012/01/31/dan-burton-retirement-indiana-gop_n_1244141.html">Editor's note:</a> Burton retired from Congress in January 2012</em> <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Jeff Flake (R-Ariz.)

    (Photo By Bill Clark/CQ Roll Call) <em><a href="http://www.huffingtonpost.com/2012/11/07/jeff-flake-election-results-2012_n_2049514.html">Editor's note:</a> Flake became a U.S. senator in Jan. 2013</em> <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Mike Conaway (R-Texas)

    (Photo By Tom Williams/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Jeff Duncan (R-S.C.)

    (Photo By Tom Williams/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. John Fleming (R-La.)

    (Photo By Bill Clark/Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Bill Flores (R-Texas)

    (Photo By Tom Williams/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Trent Franks (R-Ariz.)

    (Photo By Bill Clark/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Scott Garrett (R-N.J.)

    (Photo By Bill Clark/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Trey Gowdy (R-S.C.)

    (Photo by Chris Maddaloni/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Tom Graves (R-Ga.)

    (Photo By Bill Clark/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Wally Herger (R-Calif.)

    (Photo By Tom Williams/Roll Call) <em><a href="http://www.huffingtonpost.com/2012/01/10/wally-harger-retirement-california-republican_n_1197156.html">Editor's note:</a> Herger retired from Congress in January 2012.</em> <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Duncan Hunter (R-Calif.)

    (Photo By Bill Clark/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Lynn Jenkins (R-Kan.)

    (Photo by Scott J. Ferrell/Congressional Quarterly/Getty Images) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Jim Jordan (R-Ohio)

    (Photo By Bill Clark/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Jeff Landry (R-La.)

    (Photo By Tom Williams/CQ Roll Call) <em><a href="http://www.huffingtonpost.com/2012/12/09/charles-boustany-wins_n_2267276.html">Editor's note:</a> Landry was defeated by fellow Republican Charles Boustany in Dec. 2012's special election.</em> <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Randy Neugebauer (R-Texas)

    (Photo By Bill Clark/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Pete Olson (R-Texas)

    (Photo By Bill Clark/Roll Call via Getty Images) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Mike Pompeo (R-Kan.)

    (Photo By Tom Williams/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Bill Posey (R-Fla.)

    (Photo By Bill Clark/Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Tom Price (R-Ga.)

    (Photo By Tom Williams/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Ben Quayle (R-Ariz.)

    (Photo By Bill Clark/CQ Roll Call) <em><a href="http://www.huffingtonpost.com/2012/08/29/david-schweikert_n_1838371.html">Editor's note:</a> Quayle was defeated by David Schweikert in the Republican primary for Arizona's 6th congressional district.</em> <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Ed Royce (R-Calif.)

    (Photo by Scott J. Ferrell/Congressional Quarterly/Getty Images) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Steve Scalise (R-La.)

    (Photo by Bill Clark/Getty Images) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. David Schweikert (R-Ariz.)

    (Photo By Bill Clark/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Tim Scott (R-S.C.)

    (Photo By Bill Clark/CQ Roll Call) <em><a href="http://www.huffingtonpost.com/2012/12/17/tim-scott-senate_n_2315830.html">Editor's note:</a> Scott was appointed U.S. Senator by S.C. Gov Nikki Haley in Dec. 2012, taking the seat of Jim DeMint.</em> <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Cliff Stearns (R-Fla.)

    (Photo By Bill Clark/CQ Roll Call) <em><a href="http://www.huffingtonpost.com/2012/08/15/cliff-stearns-planned-parenthood-reelection_n_1777602.html">Editor's Note:</a> Stearns lost the Aug. 2012 GOP primary to retain his House seat.</em> <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Marlin Stutzman (R-Ind.)

    (Photo By Tom Williams/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Lynn Westmoreland (R-Ga.)

    (Photo By Bill Clark/Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Joe Wilson (R-S.C.)

    (Photo By Bill Clark/CQ Roll Call) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>

  • Rep. Todd Rokita (R-Ind.)

    (AP Photo/Michael Conroy) <a href="http://hosted-p0.vresp.com/1174985/8b2d5dc5f6/ARCHIVE">Source: American Conservative Union 2012 Rankings </a>