A Democratic congressman has launched an investigation into True The Vote, a conservative Tea Party group that has attempted to purge thousands of registered voters from voting rolls across the country ahead of the November presidential election.

The organization is pursuing an aggressive ground campaign to challenge people's right to vote based on their residency and citizenship, such as the hundreds of college students who failed to identify their dorm room numbers on voter registration applications.

In a letter to Catherine Engelbrecht, the founder of True The Vote, Rep. Elijah Cummings (D-Md.) accused the Texas-based organization of challenging the registration of thousands of legitimate voters "based on insufficient, inaccurate, and faulty evidence."

"True the Vote, its volunteers, and its affiliated groups have a horrendous record of filing inaccurate voter registration challenges, causing legitimate voters -- through no fault of their own -- to receive letters from local election officials notifying them that their registrations have been challenged and requiring them to take steps to remedy false accusations against them," wrote Cummings, the ranking minority member of the House Committee on Oversight and Government Reform.

The letter continues: "Multiple reviews by state and local government officials have documented voter registration challenges submitted by your volunteers based on insufficient evidence, outdated or inaccurate data, and faulty software and database capabilities. Across multiple states, government officials of both political parties have criticized your methods and work product for their lack of accuracy and reliability."

"Your tactics have been so problematic that even Ohio Republican Secretary of State Jon Husted has condemned them as potentially illegal," Cummings states in his letter.

Husted in August was scheduled as a featured speaker at the True the Vote Ohio State Summit, but pulled out after The Nation's Voting Rights Watch 2012 published an investigative report on the organization's practices.

A spokesman for True The Vote told the Los Angeles Times that Cummings' letter has since been sent to its legal team and that the group would be "more than happy to avail itself" of the congressional committee.

"In the interim, True The Vote invites Congressman Cummings, or any other interested parties, to participate in any training sessions in the weeks ahead," Logan Churchwell, the spokesman, told the newspaper in an email.

Cummings told The Huffington Post that it appears that True The Vote has been extremely selective in whom it targets for a challenge.

"We have asked True The Vote to provide us with documentation that shows exactly how they select folks to go after and challenge," Cummings said. Cummings said some of what he's heard about the group's strategy has been disturbing and, if true, threatens fundamental American rights.

"It does appear that they are quite selective in who they challenge, and it appears they primarily go after people who might be inclined to vote Democratic," Cummings said. The congressman said that in Ohio, for example, True The Vote has targeted nine of 13 districts won by President Barack Obama in 2008.

"It also appears they challenge, at disproportionate rates, African Americans," Cummings said, characterizing these tactics as "blatant." He questioned True The Vote's intent and said that Engelbrecht has made it public knowledge that she'd like to see Obama defeated.

Cummings said, "You would think someone trying to address voter fraud wouldn't be talking about who they want in the White House; it would be 'I want to talk about fair elections.'"

True The Vote's website describes the organization's mission as to "restore truth, faith, and integrity to our elections."

The group and its offshoots in various states have gained a reputation for aggressively challenging the legitimacy of properly registered voters. Critics say their tactics are often flawed and especially target poor and minority communities.

The group has also filed lawsuits against election officials in Ohio and Indiana, and instructs volunteers on how to use software to cross-check voter rolls against driver's license records and property records, among other databases. A Government Accountability Board in Wisconsin, where True The Vote raised questions about thousands of voter signatures, called the results of the group's process "at best flawed."

Last week, Sen. Barbara Boxer (D-Calif.) asked the Justice Department to "protect Americans from voter intimidation" in the face of "widespread efforts by Tea Party-linked groups to intimidate voters and suppress the vote, particularly in low-income and minority neighborhoods."

In a letter to Assistant Attorney General Thomas Perez, head of the Civil Rights Division of the Justice Department, Boxer asked that they uphold the tenets of the Voting Rights Act.

"No group can be allowed to intimidate or interfere with this fundamental right that is essential for American democracy," Boxer wrote.

"This type of intimidation must stop," Boxer continued. "I don't believe this is 'True the Vote.' I believe it's 'Stop the Vote.'"

According to the report in the Los Angeles Times, an Ohio offshoot of the group challenged the voting rights of eight members of a black family who were registered at an address the group identified as a vacant lot, though the address was actually the location of the home where the family had lived for some three decades.

The family represents only a few of at least 2,100 names that Tea Party groups have sought to remove from Ohio's voter rolls, according to the report.

"We're all about election integrity -- making sure everyone who votes is registered and qualified voters," Mary Siegel, one of the leaders of the Ohio effort, told the Times.

This morning on CNN's "Starting Point," Cummings again questioned the group's motives.

Voting rights advocates say True The Vote's efforts are part of a larger effort by Republicans to suppress the votes of likely Democratic voters, including the poor and racial minorities. Most notably a wave of strict voter ID laws, which require voters to present state-issued photo ID to cast a ballot, passed in 11 states.

"I believe very strongly that voting is a fundamental right, and it is not something that should be limited to a few people," Cummings told host Soledad O'Brien. "And we must address anybody who tries to deny anybody that right to vote. I consider it criminal, I consider it unpatriotic and truly offensive."