Supreme Court fight highlights US Senate race in Arizona

In one of the most closely watched contests of the cycle, Republican Sen. Martha McSally is battling Democratic opponent Mark Kelly, a former astronaut and the husband of former Rep. Gabby Giffords.

What sets this contest apart is that the winner in Arizona might be eligible to take office sooner than other newly elected senators, because McSally was appointed to fill out the term of the late Sen. John McCain after Sen. Jon Kyl, who was previously appointed to fill the seat, resigned in December 2018.

The Arizona Republic reported Friday night that if Kelly wins on November 3, he could be sworn in as soon as November 30, meaning the balance of power in the Senate would shift from the current 53 Republicans and 47 Democrats to 52 Republicans and 48 Democrats.

That difference could impact the ability of Senate Majority Leader Mitch McConnell to confirm Ginsburg's replacement because some GOP senators have expressed reluctance to filling a Supreme Court vacancy during a presidential election year.

The timing is also important and, as of this weekend, an open question. While McConnell has already committed to having a vote on whomever President Donald Trump nominates, it's not clear if a vote on final confirmation could happen in the fewer than 50 days between this weekend and Election Day.

GOP aides told CNN on Friday they were skeptical that there is enough time to confirm a nominee before November 3, given that Supreme Court picks typically take two to three months to process, according to a review of recent confirmation proceedings. But that process could be sped up if McConnell has the votes to confirm a replacement, and there is enough time to confirm someone in a lame-duck session of Congress after the November elections. The new Senate would be sworn in in early January 2021.

That calculation is further complicated if Republicans lose control of the Senate and the White House after the election -- and whether enough GOP senators would break ranks and oppose any nominee by a President who had just lost his election and a GOP Senate that just lost its majority. Democrats see flipping the Arizona seat as a key strategy to retaking the majority.

McSally, a former Air Force fighter pilot and congresswoman, weighed in Friday night calling for a vote on whomever Trump chooses.

"This U.S. Senate should vote on President Trump's next nominee for the U.S. Supreme Court," she tweeted.

The Arizona Republic newspaper made clear in its report Friday that getting Kelly sworn in then is not a done deal and may be contested.

"Two Republican and Democratic election attorneys agree that state law and Senate practice would make Kelly eligible to take over the seat once held by Sen. John McCain as soon as Nov. 30, when the state election results are expected to be canvassed," wrote the Republic's Yvonne Wingett Sanchez.

Though Trump won Arizona in 2016, Kelly has consistently been polling ahead of McSally throughout most of the summer. In a New York Times/Siena College poll on Friday, Kelly was at 50% to McSally's 42% among likely voters.