"I want to continue to [serve] the people of Georgia. We're getting ready for a good time down here to keep defending this president and keep working for the people of Georgia," Collins said in an interview on "Fox and Friends" Wednesday morning.

Collins downplayed concerns about running against a sitting Republican senator. He did not say whether he thought Trump would back his run, but said he appreciated the president's "help and support" in the past.

"I think we fought for the president, we fought for our state and we fought for this country," Collins said. "And we're going to continue to do that. I look forward to a good exchange of ideas and look forward to this election."

The bid complicates Republicans path to holding onto the seat in November, which has frustrated allies of Senate GOP leadership. Republicans are defending a 53-47 majority in the chamber — including the other Georgia Senate seat — and an expensive and high-profile fight in the Georgia special election is seen as unhelpful to their cause.

Loeffler, a wealthy finance executive, has nearly endless resources to put into her own campaign. She has already pledged to spend at least $20 million on her own bid, a figure that could easily rise in a competitive contest. Her campaign already announced plans to spend $4 million on the airwaves, and $2.6 million has already been booked for ads through mid-February playing up her support of Trump and introducing her biography to voters.

Collins will have significant roadblocks to keeping up in the resource battle. He had nearly $1.4 million in cash on hand in his federal campaign account as of last Sept. 30. His next report will be due to the FEC on Friday, which will disclose how much money he had in the bank at the end of last year.

Collins was immediately brushed back by Senate Republicans. The top staffer at the NRSC said the GOP's official campaign arm "stands firmly behind" Loeffler and said Collins' bid threatens the party's hold on not just the Senate seat — but up and down the entire ballot, including the presidential race.

“The shortsightedness in this decision is stunning," Kevin McLaughlin, the executive director of the NRSC, said in a statement. "Doug Collins’ selfishness will hurt David Perdue, Kelly Loeffler, and President Trump. Not to mention the people of Georgia who stand to bear the burden of it for years to come. All he has done is put two Senate seats, multiple House seats and Georgia’s 16 electoral votes in play.”

Collins fired back at the NRSC on Twitter, rejecting claims that his candidacy risked Republicans' position in the election.

"Don't be ridiculous, this is FAKE NEWS coming from the head of a Washington-based group whose bylaws require him to support all incumbents, even unelected ones," Collins tweeted in response to the NRSC statement.

Republicans were already preparing for battle against Collins as rumors of his impending announcement traveled around the Capitol this week. The NRSC's statement was among the first salvos from the GOP establishment. A super PAC aligned with Senate Majority Leader Mitch McConnell also criticized Collins for being "selfish."

Steven Law, the president of the McConnell-linked Senate Leadership Fund, said Loeffler, who was sworn earlier this month, "is such a warrior for the president."

"We'll have her back if she needs us," Law said.

Meanwhile, Loeffler, the newly minted incumbent, was at the White House on Wednesday for the signing of the new North American trade agreement — where she got a shoutout from the president.

"Congratulations, Kelly, really great," Trump said. "They already like you a lot. That's what the word is."

Quint Forgey contributed to this report.

