Sen. Jeff Flake'scould spur a rush of other Republican candidates who hope to take on his only announced challenger in the 2018 Arizona primary.
The freshman senator's decision came after months of statements where he said he expected a tough primary and general election race but believed he could win. Behind the scenes, though, a drumbeat of polling showed him badly damaged by comments he made about President Donald Trump in a book he released over the summer and an ongoing battle with his party's leader that began before last year's election.
Flake was, who failed in her effort to take out Sen. John McCain last year but has gained traction this year. Last week, former Trump strategist Steve Bannon attended a fundraiser for her. Ward embraced the anti-establishment, anti-incumbent wing of the party driven by Trump with an assist from Bannon.
But mainstream Republicans in Arizona believe Ward cannot beat Rep. Krysten Sinema, a moderate who is running in her primary as the only well-known Democratic candidate. They have been searching instead for another candidate who can draw support from Trump populists to take on Flake, and his decision to step aside opens the door for those efforts. In the background, the White House has also been seeking another candidate.
His departure has raised the stakes even more for what is sure to be a bitter and expensive election battle next year in Arizona as the GOP fights to hold onto a seat and the Democrats seek an opening to pick one up.
For months, the names of other potential GOP challengers have been floated, but none has entered the race. They include current state university regent Jay Heiler; former state GOP chairman Robert Graham; state Treasurer and 2016 Trump campaign chief financial officer Jeff DeWit; and Reps. Paul Gosar and Trent Franks. The other three GOP members of Arizona's House delegation could be wild cards — David Schweikert, Andy Biggs and Martha McSally.
A spokesman for GOP Gov. Doug Ducey said he was "absolutely not" considering running for Senate.
Republican political consultants in Arizona are split on whether there will truly be a rush of candidates.
"Somehow they all seem unlikely to me," Constantin Querard, a top campaign consultant, said of those already in the mix. "Because if you were not going to run against a mortally wounded candidate with the support of the president and millions of dollars of outside spending, why would you suddenly be interested in the race without all of those things?"
But Chuck Coughlin, another longtime Republican campaign consultant who did polling that showed Flake in bad trouble, isn't so sure. He said a candidate who can draw support from the pillars of the Republican political establishment in Arizona — Flake, Sen. John McCain, Gov. Doug Ducey and former Gov. Jan Brewer — would be the one to take on Ward in a primary.
"The question is, who can mostly closely thread the needle there between Trump, McCain, Flake, Brewer, the current governor," Coughlin said. "Who is that?"
"One thing I'd guarantee you is Kelli Ward will face a primary opponent, there's no doubt in my mind on that," he added.
Another potential problem for Arizona Republicans is the health of McCain, who was diagnosed this summer with an aggressive form of brain cancer and acknowledges his prognosis is poor. A vacancy in McCain's seat before April means a second Senate race would be on the 2018 ballot.
As recently as early this month, Flake told The Associated Press he was in it to win in 2018 and discounted both Ward and Sinema.
"John McCain at this position was down by double digits to Kelli Ward, down by double digits to any generic Democrat," he said in an Oct. 9 interview. "He ended up winning by double digits in both the primary and the general because he ran a good campaign, and we're going to try to do the same thing."
By Tuesday, things were different for Flake.
"If I could run the kind of race I'd like to run and believe I could win a Republican primary, I might go forward," he told reporters at the U.S. Capitol after his announcement. "These days, it seems that unless you're on every policy the president has, then somehow you're not a conservative."
Flake is a throwback Arizona conservative, with strong small government credentials but a Libertarian streak along the lines of the late Sen. Barry Goldwater. He sparred with the president over free trade, which he supports, immigration reform and opening relations with Cuba.
But those positions put him in the crosshairs of Trump and the grassroots populists he courts.