Republicans are already scrambling for a plan to fill Jeff Flake's Senate seat

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Jeff Flake.

• Jeff Flake's retirement creates a wide open race for Arizona's Senate seat in 2018.
• Multiple Republican members of Congress have been floated as potential candidates.
• Far-right outsider candidates could also jump in the race.

WASHINGTON - With Sen. Flake's decision to not seek reelection in Arizona next year, the Grand Canyon State's congressional delegation was sent into a frenzy of speculation about who might throw their hat in the ring for what will be a high-profile 2018 race.

Flake made the announcement to retire after just one term on Tuesday, citing as a key reason the deterioration of political discourse, much of which he attributes to President Donald Trump.

"The notion that one should stay silent as the norms and values that keep America strong are undermined and as the alliances and agreements that ensure the stability of the entire world are routinely threatened by the level of thought that goes into 140 characters - the notion that one should say and do nothing in the face of such mercurial behavior is ahistoric and, I believe, profoundly misguided," Flake said on the Senate floor.

Following the announcement, speculation mounted about a Republican successor.

"There's a lot of rumors right now," said Arizona Rep. Andy Biggs. "It was just an hour and a half ago and already my phone is blowing up with all kinds of suggestions with all kinds of people."

Rep. Martha McSally, whose name has been floated as a candidate, quickly entered and exited the House floor to avoid interacting with reporters about her 2018 ambitions.

But Ohio Rep. Steve Stivers, who chairs the National Republican Congressional Committee (NRCC), told Business Insider he hopes McSally remains a member of the House for the next election, adding he believes the GOP has a deep bench of prospective candidates to potentially fill her seat.

"Martha's a great candidate but there's other good candidates that live there," Stivers said. "I hope Martha stays in the Congress, but if she decides she wants to run for the Senate, we'll have a good candidate and we'll win."

"We're lucky to have a lot of talent in Arizona, a lot of great members, and if one of them decides to do it, I feel pretty confident we can hold all our seats in Arizona," Stivers said, noting Arizona's considerable Republican bent.

In addition to McSally, a name that immediately attracted speculation was Rep. David Schweikert, an influential member of the Financial Services Committee.

"I think we'll have a little bit of a family discussion with the Republican members and see if anyone has the burning ambition," Schweikert told reporters Tuesday.

But the flurry of House Republicans who might jump in could extend even further. Rep. Ruben Gallego, a Democrat serving in Arizona, told reporters, "I think you're gonna see the Arizona congressional Republican delegation emptying out pretty quickly."

Outside the current Arizona congressional delegation, among the names floated were former Governor Jan Brewer and former Maricopa County Sheriff Joe Arpaio, who was pardoned by Trump in August of a conviction for violating court orders on a racial profiling law.

"They wouldn't be able to make it," Gallego said of Brewer and Arpaio.

Arpaio told the Washington Examiner he is considering a run and has spoken with former White House chief strategist Steve Bannon.

"I mean if [Arpaio] wins a primary that's better," Gallego added. "We could definitely beat him like a drum in the general."

On the Democratic side of the race, the only major candidate to declare is Rep. Kyrsten Sinema, who is known for being one of the most moderate members of Congress. Sinema has already received broad support among her colleagues, including Gallego, who said he is supporting her but has yet to officially endorse.