Just before U.S. Rep. Doug Collins stepped up to the microphone to deliver a morning invocation, one of the most powerful politicians in Georgia offered a personal story about the Gainesville Republican.

"I have a confession, he is my friend. He is my friend," House Speaker David Ralston said, gesturing toward the lanky congressman at his right. "He has stood by me when few would, and I don't forget that."

It’s not quite an endorsement of Collins’ plan to challenge U.S. Sen. Kelly Loeffler, a wealthy financial executive picked by Gov. Brian Kemp, but it might as well have been.

And it underscored the tense decisions in private and in public that will force state Republicans to draw battle lines within their own party at a precarious political moment.

MoreThe Jolt: Fights over budget, U.S. Senate seat threaten 2020 session

MoreCollins' bid for Senate opens up another Georgia House seat 

MoreCollins will soon launch campaign for US Senate in Georgia

Over the next few weeks, conservatives will be pressured to choose: Will they support Collins and his devoted grassroots supporters or a brand-new senator with the full backing of Georgia’s governor? And many squeamish Republicans will be caught between the two warring camps.

"Every time you have an election going, there are doubts and questions raised," said state Rep. David Clark, a Buford Republican who has not endorsed either candidate. "Who is going to win? Will there be a runoff? But, look, it's America and they have a right to run."

Collins hasn’t formally entered the race yet, but The Atlanta Journal-Constitution first reported Monday that he was expected to soon announce his candidacy — and that he was making calls to friends and supporters informing them about his decision.

"There will be more coming later," Collins said Tuesday shortly after his invocation to the Georgia House, which focused on spiritual growth and bipartisanship. Pressed on whether the latter was a preview of his campaign mantra, Collins said: "When has it not been part of my message?"

A battle of wills quickly emerged between Collins and Kemp, who has declined to comment about the challenger who threatens the most significant appointment he’s made since taking office. Asked Tuesday to chime in on Collins’ decision, Kemp pursed his lips and shook his head.

Georgia Democrats were eager to feast on the Republicans’ internal warfare that could boost their own candidate. Since the race is a special election with no primary to filter out nominees, the GOP division heightens the possibility that a unifying Democratic candidate can win the race outright.

"This raised the stakes in the U.S. Senate race. In all the years I've been here, I've never seen a Senate race elevated to this level," said state Rep. Calvin Smyre, the longest-serving lawmaker in the Legislature. "It's a numbers game, and getting 51% of the vote is going to be impossible."

Still, the Democrats have their own internal commotion to sort out. Matt Lieberman, an entrepreneur, and Ed Tarver, a former federal prosecutor, plan to qualify. And the Rev. Raphael Warnock is set to soon enter the race and position himself as the front-runner with support from leading party figures.

‘His prerogative’ 

Many Republicans, meanwhile, were eager to sidestep discussion about which Senate candidate they will back. Although many top state Republican officials have met with Loeffler, who was little known in political circles before her appointment, only a handful have endorsed her.

Among those on the sidelines is U.S. Sen. David Perdue, a former Fortune 500 chief executive who prefers to keep his focus on his own re-election battle in November. He faces three well-financed Democrats who are dueling for the chance to challenge him.

“That’s his prerogative,” Perdue said shortly after the AJC published a story about Collins running, before the senator pivoted to talk about another subject.

Others might not be so circumspect. Kemp plans to leverage his campaign war chest and his formidable approval rating — his tally in an AJC poll this month was highest among any politician polled — to pressure his allies to back Loeffler.

And outside groups are fast staking out positions, too. U.S. Sen. Todd Young, the chairman of the National Republican Senatorial Committee, told CNN that the GOP’s Senate arm is “fully committed” to Loeffler and that he’s “not concerned” about Collins’ challenge.

The U.S. Chamber of Commerce and the conservative Club for Growth also reinforced support for Loeffler, as did several of her U.S. Senate colleagues.

Among them is Marsha Blackburn of Tennessee, who urged her colleagues on Twitter to “do more than talk about supporting strong conservative women.”

“We need to DO it,” Blackburn said.

Loeffler has also dipped deeper into her bank account — she plans to spend at least $20 million to finance her campaign — for a round of advertisements. Shortly after Collins spoke to the House, her campaign unveiled a TV ad emphasizing her rural roots.

Collins, meanwhile, will look to lock up support from fellow U.S. House members, conservative activists from his base in North Georgia and former colleagues in the state Legislature.

Among them is Ralston, whom Collins supported a decade ago in his first, ill-fated attempt to win the speaker's gavel. Ralston would capture the job a few years later, and he remains so close to Collins that he's now pushing legislation that would force Loeffler into a primary against the congressman.

In remarks shortly after Collins spoke, Ralston punctuated the tight spot he and other Republican officials are now in.

“The only endorsement I’m doing is to keep the Republican majority in the Statehouse. That’s my No. 1 overriding, all-consuming goal and objective,” Ralston said. “At the same time, I’m not going to run away from the fact that Doug Collins has been my friend for almost 20 years.”

Staff writers Ariel Hart and Tia Mitchell contributed to this article.