Matt Bevin, Sen. Mitch McConnellAddison (Mitch) Mitchell McConnellSessions: 'We should be like Canada' in how we take in immigrants NSA spying program overcomes key Senate hurdle Overnight Finance: Lawmakers see shutdown odds rising | Trump calls for looser rules for bank loans | Consumer bureau moves to revise payday lending rule | Trump warns China on trade deficit MORE’s (R-Ky.) primary challenger, raised nearly $900,000 in the final three months of the year, his campaign announced Thursday.

Bevin’s campaign said he has now received donations from more than 15,000 contributors, a number they believe is an indication of McConnell’s massive unpopularity not just in Kentucky but nationwide. All of the $900,000 sum came from outside contributors, a departure from his third-quarter fundraising report, which revealed a majority of his $800,000 sum raised was his own money he contributed to his campaign.

Bevin said he was “encouraged” by the amount, and that he believes voters are beginning to realize he has a better shot at keeping the seat than McConnell does.

"As voters learn more about Sen. McConnell's big-government record of voting for bailouts, tax increases, NSA spying, and amnesty, they realize that the only Republican in Kentucky that can lose this Senate seat is the man who's currently in it," he said.

Bevin did not, however, release how much cash he has on hand.

Neither McConnell nor his likely Democratic opponent, Kentucky Secretary of State Alison Lundergan Grimes, have released their fourth quarter fundraising hauls yet, but they were both in better financial condition than Bevin at the start of October.

McConnell posted just under $10 million cash on hand, while Lundergan Grimes had just under $2 million in the bank, after outraising McConnell in the third quarter.

But Bevin has the support of at least one deep-pocketed outside group in the primary: The Senate Conservatives Fund, which says it has invested nearly $1 million in the challenger's campaign last year, more than $450,000 in contributions from donors.

Bevin's campaign said SCF members contributed $429,000 to his campaign in the fourth quarter. And McConnell’s campaign suggested the challenger’s $900,000 fourth-quarter sum was unimpressive because much of it may have come from SCF.

“When a single fundraising group from Washington, D.C., who is responsible for numerous Democratic Senate victories raises more than half your money it’s a clear sign of a manufactured candidacy,” McConnell spokeswoman Allison Moore said. “For six months Kentuckians have been trying to determine whether Matt Bevin’s campaign is a stalking horse for Democrats or a payoff for a small cadre of consultants in Washington, and today we’ve learned that it’s both.”

But Bevin's campaign dismissed the McConnell campaign's assertion, with spokeswoman Rachel Semnel saying the campaign is "proud" of the support from conservatives "who know we can do better than Mitch McConnell in the U.S. Senate."

--This piece was corrected at 12:30 p.m. to reflect the sum SCF contributed to Bevin.