Republican presidential candidate, Rep. Ron Paul, R-Texas, listens as campaign chairman Jesse Benton has a word with him as he signs autographs at the Cass County Community Center in Atlantic, Iowa, Thursday, Dec. 29, 2011. (AP Photo/Charles Dharapak)

This story was originally posted at 12:45 p.m.

Jesse Benton, a longtime ally of Sen. Rand Paul (R-Ky.) who is heading up a super PAC supporting his presidential campaign, has been indicted by a federal grand jury, the Justice Department said Wednesday, on charges that he concealed payments made to a former Iowa state senator during the 2012 presidential campaign in order to win his support.

The indictment marks a new complication for Paul, whose political future is on the line in 2016. He is hoping to hold onto his U.S. Senate seat, which is up for reelection,  if he does not win the GOP White House nomination.

The charges against Benton, a member of the Paul family by marriage, stem from an endorsement-for-pay scheme during the 2012 campaign of former Republican congressman Ron Paul of Texas, which Benton chaired. Two other former Ron Paul campaign officials were indicted, including John Tate, who was Ron Paul's campaign manager and is now also involved with heading up the pro-Rand Paul super PAC; and Dimitri Kesari, who was Ron Paul’s deputy national campaign manager.

The indictment charges the defendants with conspiracy, causing false records to obstruct a contemplated investigation and causing the submission of false campaign expenditure reports. It alleges they paid more than $70,000 to then-Iowa state senator Kent Sorenson in exchange for his support. The indictment accuses the men of concealing their payments from the Federal Election Commission and the FBI.

“Federal campaign finance laws are intended to ensure the integrity and transparency of the federal election process,” said Assistant Attorney General Leslie R. Caldwell in a statement announcing the indictment. “When political operatives make under-the-table payments to buy an elected official’s political support, it undermines public confidence in our entire political system.”

Both Ron Paul and a spokesman for Rand Paul issued statements accusing the Justice Department of a politically-motivated attack.

"I am extremely disappointed in the government's decision," Ron Paul said in a statement. "I think the timing of this indictment is highly suspicious given the fact that the first primary debate is tomorrow. My thoughts and prayers are with the families of those involved."

Rand Paul's campaign, through an unnamed spokesman, offered similar criticism of the timing. "Senator Rand Paul is disappointed that the Obama justice department chose to release this just prior to the highly anticipated first Republican presidential debate," the campaign said. "It certainly appears suspiciously timed and possibly, politically motivated. Additionally, these actions are from 2012 and have nothing to do with our campaign."

Benton's attorney Roscoe C. Howard, Jr. said in a similar statement that his client would be vindicated. "Mr. Benton is eager to get before an impartial judge and jury who will quickly recognize this for what he believes it is: Character assassination for political gain," he said.

Benton is married to the granddaughter of Ron Paul, Rand Paul's father. He's been a close family confidant since 2007. The case has its roots in a pay-for-endorsement scheme that roiled the Iowa Republican caucuses in 2012.

Last August, Sorenson pleaded guilty to concealing campaign expenditures and obstructing justice as part of the scheme, admitting in federal district court that Ron Paul’s presidential campaign secretly paid him $73,000 after he dramatically dropped his backing of then-Rep. Michele Bachmann (R-Minn.) in late 2011 and endorsed Paul’s White House bid.

At the time of his flip, a furious Bachmann charged that Sorenson was being paid to back Paul -- an accusation that Sorenson, Paul and his campaign officials all initially denied.

In fact, Sorenson was first paid by Bachmann’s campaign and her PAC, which routed him between $7,000 and $7,500 a month for most of 2011, according to court documents. Then in December 2011, after two months of secret negotiations with Paul’s campaign, the state senator met with a Paul political operative at a restaurant in Altoona, Iowa, and agreed to change his allegiance. The operative gave Sorenson’s wife a check for $25,000 to secure Sorenson’s support. (The check was apparently never cashed.)

Bachmann's political PAC, reached late on Wednesday, declined to comment on the indictment.

The court filings did not identify the Paul operative who gave Sorenson a check, but in a recording of a phone call posted by TheIowaRepublican.com, Sorenson identified him as Kesari. TheIowaRepublican.com and OpenSecrets.org, the Web site of the nonpartisan research group Center for Responsive Politics, also revealed emails in which representatives of Paul and Sorenson allegedly discussed his demands for payment.

After Sorenson publicly switched his endorsement, Paul’s campaign routed the state senator a total of $73,000 in 2012, transferring the payments through a film production company and another company to conceal the intended recipient, according to court filings. Sorenson wanted the payments kept secret because of Iowa Senate ethics rules that prohibit sitting senators from accepting payments from a political campaign, according to court papers.

After Sorenson’s guilty plea last summer, Benton resigned from his post as the strategist for now-Senate Majority Leader Mitch McConnell’s reelection campaign. McConnell had sought Benton's support to help fend off tea party challengers in the Republican primary. In a statement at the time, Benton cited “inaccurate press accounts and unsubstantiated media rumors about me and my role in past campaigns that are politically motivated, unfair and, most importantly, untrue.”

Tate has been paid by nearly $35,000 this year by America’s Liberty, the pro-Paul super PAC, campaign finance records show. Benton's firm, Titan Strategies, has also received about $35,000 this year from the organization for consulting fees. In addition, the company was paid another $27,500 for media buys.

There are two other super PACs -- which can raise and spend unlimited amounts to help candidates win but are barred from coordinating strategy with them --

Benton was allegedly at the heart of the 2012 campaign scheme, according to the grand jury indictment unsealed Wednesday. He emailed Sorenson on Oct. 31, 2011, and offered to match the money he was making from Bachmann’s campaign if he switched his endorsement to Paul, according to the filing.

Two months later, Benton, Tate and Kesari helped edit Sorenson’s press release announcing he was backing Paul, the indictment alleges.

Benton then allegedly told campaign officials to hold off on a wire transfer to Sorenson so the payment would not show up that quarter’s Federal Election Commission report. When a finance staffer inquired about “Dimitri’s mystery wire” for $25,000, Tate allegedly wrote back, “There will not be the $25K dimitri wire for now. Wipe it off the books.”

Payments to Sorenson were then routed through two companies to mask their destination, the indictment said.

Once the FBI began investigating the case, Benton falsely denied that the Paul campaign had paid Sorenson, according to the filing. “I am not splitting hairs,” he allegedly told FBI officials last July. “Sorenson was not getting paid.”

The scheme was exposed in part because of a whistleblower in the Paul campaign named Dennis Fusaro, who revealed e-mails and phone calls between Sorenson and the campaign.

"It's very sad, and I feel bad for them," said Fusaro. "I wish that this didn't happen, because the political class will have a field day with this."

 -- Anu Narayanswamy contributed to this post