This race could decide who controls the U.S. Senate; here's where things stand

Potentially vulnerable and confronting a volatile political atmosphere, U.S. Sen. Jeff Flake has started taking his 2018 re-election race seriously.

Flake, R-Ariz., one of two incumbent GOP senators who national Democrats see as beatable in 2018, reported raising nearly $1.3 million in January, February and March. He hosted former President George W. Bush for a fundraiser in April. Next month, Mitt Romney, the 2012 Republican presidential nominee, will join Flake for fundraising events in Phoenix and Tucson.

In a Senate that Republicans control with a 52-vote majority, the loss of just a few seats could put the chamber in the hands of the Democrats. Besides Flake, Sen. Dean Heller, R-Nev., also is considered vulnerable.

Flake already has two challengers: Kelli Ward, the former state senator from Lake Havasu City who unsuccessfully ran against U.S. Sen. John McCain in last year's GOP primary, now is running against Flake. Deedra Abboud, a Phoenix attorney and community activist, is seeking the Democratic nomination for Senate.

But Flake so far has not had a high-profile name enter the race. 

"Like almost every Senate race this cycle, it is shaping up slowly," said Jennifer Duffy, who analyzes Senate races for the influential and nonpartisan Cook Political Report in Washington, D.C. "Many potential candidates in both parties are eyeing the horizon to get a sense of what the political environment may look like a year from now."

U.S. Rep. Kyrsten Sinema, D-Ariz., perhaps the most talked-about name on the Democratic side, on Wednesday appeared to scuttle the idea of taking on Flake.

“You know, I'm running for re-election and ... it has been really the greatest honor of my life to serve Arizona's 9th (Congressional) District,” Sinema said in an interview on Phoenix radio station KTAR-FM in response to a question about running for the Senate. "... I'm overcome with just gratitude about the role that I'm able to play for Arizona. And it's my honor. So I'm running for re-election. Very happy, very proud to do it."

But 12 News reported Thursday that, despite the plain reading of her remarks, she may not have ruled out a Senate candidacy after all. "I've said what I always say. I'm currently running for re-election," she told Brahm Resnik of 12 News.

Sinema's campaign reported having $2.8 million on hand at the end of March, which she could spend in a Senate race; Flake's campaign reported having only $1.8 million.

While it is still early in the 2018 cycle, former U.S. Rep. Ann Kirkpatrick, D-Ariz., announced her 2016 Senate candidacy at a similar point — May 26, 2015.

In Arizona's 2012 Senate race, former U.S. Surgeon General Richard Carmona announced his Democratic candidacy in November 2011.

"Given that Flake has a primary, a candidate could conceivably wait until early next year," Duffy said.

Political observers said Friday that Sinema probably doesn't have anything to lose by playing it cool and waiting to see how the next few months unfold. It may turn out to be a better bet for her to instead run for the Senate in 2022. McCain, R-Ariz., has not said whether he plans to retire after his current sixth term, but he will be 86 when it ends and many are anticipating that he will.

But there's also a chance Republican Donald Trump's presidency could "go up in flames," one political expert said, which could help make 2018 a big Democratic year. The party not occupying the White House generally picks up congressional seats during midterm elections anyway, but GOP efforts to roll back former President Barack Obama's Affordable Care Act have further angered and energized Democratic activists and voters.

"I think a lot of people are sort of sitting back and just seeing how this 'Obamacare' repeal thing is going to play out," said David Berman, a senior research fellow at Arizona State University's Morrison Institute for Public Policy and a professor emeritus of political science. "It could hurt the Republicans potentially and get some more people interested in the race on the Democratic side, and on the Republican side, too."

Flake in 2016 got some national attention as a high-profile Republican detractor of Trump. He never endorsed Trump and did not vote for him. Now he has to worry about backlash from Trump supporters.

Flake's longtime support of comprehensive immigration reform, which opponents decry as "amnesty," also has turned off some of the conservative base.

Though Ward staked out her ground in the GOP primary early — she announced in October — other Republicans could still get in. Arizona State Treasurer Jeff DeWit, who is close to Trump, could try to unseat Flake with the president's blessing. However, DeWit also could avoid the race by opting to join the Trump administration in some capacity.

Nowicki is The Arizona Republic's national political reporter. Follow him on Twitter at @dannowicki and on his official Facebook page.