Sen. Mark Kelly said he'll support changing the Senate filibuster if Republicans block Democrat-backed election bills Wednesday night, erasing speculation about whether he might buck Democratic leadership on the controversial vote. 

"My year in the Senate has shown me how dysfunctional this place can be, and how that prevents progress on issues that matter to Arizonans," Kelly, D-Ariz., who faces a difficult reelection this year, said. "We’re seeing that now, as voting rights legislation remains blocked while partisan politicians work to undermine Arizona’s successful vote-by-mail system and create more barriers to vote."

Sen. Mark Kelly, D-Ariz., walks to his car as he prepares to depart the U.S. Capitol following the conclusion of the second impeachment trial of former President Donald Trump on February 13, 2021 in Washington. Kelly said Wednesday he is willing to vote to get rid of the Senate filibuster. (Photo by Joshua Roberts/Getty Images)

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Kelly added: "If campaign finance and voting rights reforms are blocked again this week, I will support the proposed changes to pass them with a majority vote." 

Republicans are expected to vote either unanimously or nearly unanimously against ending debate on Democrats' bills – which they combined into one piece of legislation – denying the 60 votes needed to advance them.

Kelly is one of several moderate Democrat senators who were cool to the idea of ditching the legislative filibuster at the beginning of this Congress. But one by one, most of those moderates came out in favor of some kind of filibuster change.

Senate Majority Leader Chuck Schumer

Senate Majority Leader Chuck Schumer, D-N.Y., waits to speak during an event to mark one year since the U.S. Capitol insurrection on Capitol Hill in Washington, Jan. 6, 2022. (AP Photo/Susan Walsh, Pool)

But Kelly remained noncommittal on the issue for months – until Wednesday, hours before Majority Leader Chuck Schumer, D-N.Y., is expected to try to change the Senate filibuster on a party-line vote using the "nuclear option." 

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The Arizona senator's statement leaves Sens. Joe Manchin, D-W.Va., and Kyrsten Sinema, D-Ariz., isolated as the only Senate Democrats expected to vote against nuking the filibuster. Manchin is expected to speak on the issue on the Senate floor later Wednesday. Sinema addressed her opposition to changing the filibuster last week.

"There's no need for me to restate my longstanding support for the 60-vote threshold to pass legislation. There's no need for me to restate its role in protecting our country from wild reversals of federal policy," Sinema said on the Senate floor. 

President Biden boards Air Force One at Brussels Airport in Brussels, Tuesday, June 15, 2021. Biden said the Senate should ditch the filibuster in order to pass election bills. (AP Photo/Patrick Semansky)

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"Today marks the longest time in history that the Senate has been equally divided," she added. "The House of Representatives is nearly equally divided as well. Our mandate, it seems evident to me, [is] work together and get stuff done for America."

Schumer, meanwhile, is arguing that it's fundamentally unfair that Republican-controlled state houses can pass election laws on simple majority votes while the Senate cannot do the same. But his gambit is doomed to fail since he can't get all of his senators on board with the plan in the 50-50 Senate.