The Internal Revenue Service has for the past two years been investigating an association of roughly 1,500 conservative-minded individuals in Hollywood, causing a few to wonder whether politics has played a role in the investigation.

Named for Abraham Lincoln, the first Republican president, “Friends of Abe” is a secretive and very private club for one of the rarest commodities in Hollywood: Conservative entertainers.

One of the Few Conservative Groups in Hollywood Has Been Under Investigation by the IRS for Nearly Two Years

Jon Voight accepts the award for best supporting actor in a series, miniseries or TV movie for “Ray Donovan” during the Golden Globe Awards at the Beverly Hilton Hotel, Jan. 12, 2014 in Beverly Hills, Calif. (Getty Images)

The group, which was founded approximately nine years ago, “fiercely protects” its membership list, according to The New York Times. It does this to avoid having its members blackballed in the notoriously left-leaning industry. Still, a few notable stars, including Gary Sinise, Jon Voight and Kelsey Grammer, have made their membership in the conservative group public knowledge.

But why has the IRS been investigating Friends of Abe? Simple: The group applied two years ago for 501(c)(3) tax-exempt status, which is far more restrictive than the regular 501(c)(4) status requested by many of the conservative groups targeted by the IRS.

The application has been under review ever since.

“Certainly, it’s been a long process,” Jeremy Boreing, executive director of Friends of Abe, told the Times. “Friends of Abe has absolutely no political agenda. It exists to create fellowship among like-minded individuals.”

The specific tax-exempt status requested by Friends of Abe, which would allow members to claim a tax deduction, prohibits the group from participating in or hosting any form of partisan activity. This is what the IRS is primarily interested in, according to sources familiar with the situation.

The IRS has repeatedly questioned the group about its membership criteria and its various social events.

Further, the IRS questioned the group at length last week about its meetings with well-known conservatives, including Wisconsin Rep. Paul Ryan, former Michigan Rep. Thaddeus McCotter and former Republican presidential candidate Herman Cain.

Friends of Abe hosted Cain in 2011 when he was still a candidate, prompting questions about whether it should be considered a political event.

It’s not unusual for a tax-exempt group to invite candidates to speak at events, and it’s not unusual for the IRS to scrutinize such events.

Friends of Abe has also hosted events that included meetings with Republican strategist Karl Rove, pollster Frank Luntz, Minnesota Rep. Michele Bachmann, House Speaker John Boehner and conservative commentators Ann Coulter and Mark Levin.

The IRS’ investigation into the group’s tax-exempt application at one time involved a request for “enhanced access” to Friends of Abe’s security-protected website, the Times reported. The group rejected this request.

One of the Few Conservative Groups in Hollywood Has Been Under Investigation by the IRS for Nearly Two Years

Actor and musician Gary Sinise has made no secret of his political leanings. (Getty Images)

Giving the IRS enhanced access to its website would have meant have given the federal agency access to the group’s members list. The request, according to the tax experts who spoke to the Times, was unusual. The experts added that the IRS already had access to the site’s basic levels, which is ordinarily all that is required in a 501(c)(3) investigation.

Nevertheless, Friends of Abe, which has practically no formal structure, operates as if it were a nonprofit, even as the IRS investigation continues to plod along at a snail’s pace. Should the IRS deny the group its tax-exempt status, it means Friends of Abe would not be able to receive tax-deductible contributions.

Click here to read the full New York Times report.

Follow Becket Adams (@BecketAdams) on Twitter