(RNS) President Obama's support among Catholic voters has surged since June, according to a new poll, despite a summer that included the Catholic bishops' religious freedom campaign and the naming of Rep. Paul Ryan, a Catholic, as the GOP's vice-presidential candidate.

On June 17, Obama held a slight edge over Mitt Romney among Catholics (49-47 percent), according to the Pew Research Center. Since then, Obama has surged ahead, and now leads 54-39 percent, according to a Pew poll conducted on Sept. 16.

Among all registered voters, Obama leads Romney 51-42 percent, according to Pew.

Obama and Romney are essentially tied among white Catholics, which some pollsters call the ultimate swing group.

On Monday (Sept. 24) Romney unveiled his Catholics for Romney Coalition, which includes numerous politicians, beer magnate Pete Coors and Princeton University intellectual Robert P. George. The Obama campaign also has a Catholic coalition.

From June 21-July 4, the U.S. Catholic bishops held a "Fortnight for Freedom," with Masses, prayer groups and presentations in dozens of dioceses nationwide. The campaign was directed in part against an Obama administration mandate that requires some religious institutions, such as colleges and hospitals, to provide cost-free contraception coverage to employees.

John C. Green, an expert on religion and politics at the University of Akron in Ohio, said Obama's surge among Catholic voters does not mean the bishops' campaign was ineffective. But religious freedom is not the most salient issue for Catholics during an election dominated by economic concerns, he said.

"It's not the issue that most middle-of-the-road Catholics are responding to," Green said.

In mid-August, Romney named Ryan, a congressman from Wisconsin and lifelong Catholic, as his vice-presidential nominee. While many conservative Catholics cheered the move, Romney received no "Catholic bounce" from selecting Ryan, according to the Pew poll. Obama's vice-presidential running mate, Joe Biden, is also Catholic.

Liberal Catholics, including some nuns, have chastised Ryan for using his Catholic faith to defend his GOP budget plan, which lowers taxes on the wealthy while cutting programs for the poor.

Among white evangelicals, another crucial religious constituency, Romney's support has inched up since July, from 69 to 74 percent, according to the Pew poll, while Obama's percentage declined.

Despite concerns that Obama's support for same-sex marriage would alienate African-American Protestants, 95 percent still back Obama over Romney.

Obama also leads among Americans with no religious affiliation, 65-27 percent. Romney leads among Americans who attend worship services at least weekly, 51-42 percent.

The margin of error for the September survey of Catholic voters is plus or minus 5.1 percentage points, according to Pew.

Click through the slideshow to see most and least Catholic states in the United States:

Loading Slideshow...
  • Massachusetts

    44,905 Catholic adherents per 100,000 people.

  • Rhode Island

    44330 Catholic adherents per 100,000 people.

  • New Jersey

    36,799 Catholic adherents per 100,000 people.

  • Connecticut

    35056 Catholic adherents per 100,000 people.

  • New York

    32443 Catholic adherents per 100,000 people.

  • Illinois

    28439 Catholic adherents per 100,000 people.

  • New Mexico

    28407 Catholic adherents per 100,000 people.

  • Pennsylvania

    27578 Catholic adherents per 100,000 people.

  • California

    27469 Catholic adherents per 100,000 people.

  • Louisiana

    26490 Catholic adherents per 100,000 people.

  • Wisconsin

    25,066 Catholic adherents per 100,000 people.

  • North Dakota

    24,881 Catholic adherents per 100,000 people.

  • New Hampshire

    23,626 Catholic adherents per 100,000 people.

  • Minnesota

    21,689 Catholic adherents per 100,000 people.

  • Vermont

    20,503 Catholic adherents per 100,000 people.

  • Nebraska

    20,414 Catholic adherents per 100,000 people.

  • Delaware

    20,328 Catholic adherents per 100,000 people.

  • Texas

    18,586 Catholic adherents per 100,000 people.

  • Hawaii

    18,350 Catholic adherents per 100,000 people.

  • South Dakota

    18,286 Catholic adherents per 100,000 people.

  • Michigan

    17,375 Catholic adherents per 100,000 people.

  • Ohio

    17,272 Catholic adherents per 100,000 people.

  • Nevada

    16,703 Catholic adherents per 100,000 people.

  • Iowa

    16514 Catholic adherents per 100,000 people.

  • Colorado

    16138 Catholic adherents per 100,000 people.

  • Kansas

    14952 Catholic adherents per 100,000 people.

  • Arizona

    14549 Catholic adherents per 100,000 people.

  • Maryland

    14503 Catholic adherents per 100,000 people.

  • Maine

    14311 Catholic adherents per 100,000 people.

  • Florida

    13371 Catholic adherents per 100,000 people.

  • Montana

    12898 Catholic adherents per 100,000 people.

  • District of Columbia

    12622 Catholic adherents per 100,000 people.

  • Missouri

    12094 Catholic adherents per 100,000 people.

  • Washington

    11664 Catholic adherents per 100,000 people.

  • Indiana

    11532 Catholic adherents per 100,000 people.

  • Wyoming

    10862 Catholic adherents per 100,000 people.

  • Oregon

    10408 Catholic adherents per 100,000 people.

  • Virginia

    8422 Catholic adherents per 100,000 people.

  • Kentucky

    8291 Catholic adherents per 100,000 people.

  • Idaho

    7872 Catholic adherents per 100,000 people.

  • Alaska

    7162 Catholic adherents per 100,000 people.

  • Georgia

    6156 Catholic adherents per 100,000 people.

  • Utah

    5793 Catholic adherents per 100,000 people.

  • West Virginia

    5173 Catholic adherents per 100,000 people.

  • Oklahoma

    4756 Catholic adherents per 100,000 people.

  • Arkansas

    4206 Catholic adherents per 100,000 people.

  • Alabama

    4198 Catholic adherents per 100,000 people.

  • North Carolina

    4121 Catholic adherents per 100,000 people.

  • South Carolina

    3929 Catholic adherents per 100,000 people.

  • Mississippi

    3791 Catholic adherents per 100,000 people.

  • Tennessee

    3504 Catholic adherents per 100,000 people.

Also on HuffPost: