With the U.S. House expected to vote this week on articles of impeachment for President Donald Trump, eyes now turn to Sen. Kyrsten Sinema to see where her vote will swing.
Sinema last year won an open Senate seat by a tight margin, making her the first out bisexual U.S. senator, and since became one of the most moderate members of the Democratic caucus. Now national analysts consider the Arizonan one of the chief Democrats to watch in the Senate, along with West Virginia's Joe Manchin and Alabama's Doug Jones.
There's also been attention on three Republican senators: Utah's Mitt Romney, Alaska's Lisa Murkowski, and Maine's Susan Collins.
But the fact that Sinema's vote may be in play could reveal a fracture in Democratic unity on a significant political issue, according to a number of analysts.
"Democrats should be hopeful of picking off Sen. Martha McSally (R-Ariz.) in what is an election year for her," writes The Washington Post, referencing the Republican Sinema defeated but who still ended up appointed to Arizona's other Senate seat, "but the more likely crossover vote might be from Democratic Sen. Kyrsten Sinema."
Closer to home, The Arizona Republic's Laurie Roberts also wrote that Sinema's vote may not be exactly what Democrats expect.
"She may be the first Democrat Arizona has sent to the Senate in 30 years, but she is not exactly a Democrat's Democrat," Roberts wrote, noting Sinema voted to confirm Attorney Gen. William Barr.
She was also one of just three Democratic senators to vote against the progressive "Green New Deal." The other two? Manchin and Jones.
Indeed, out analyst Nate Silver's team at FiveThirtyEight, which tracks all political statistics imaginable, finds Sinema is the number 2 Democrat in the Senate when it comes to supporting President Trump's positions, something she has done 21 percent of the time. That's behind only Manchin.
"I doubt electoral considerations matter that much to either Manchin nor Sinema -- they aren't up for reelection until 2024, when Trump's impeachment will likely be a distant memory," writes FiveThiryEight's Perry Bacon Jr. "So I would bet that both Manchin and Sinema vote against Trump's removal, preserving their brands as separate from the broader Democratic Party."
Arizona-based PBS program Cronkite News has tracked statements on impeachment from all federal officials in the state but has found neither Sinema not McSally making any public statements on the matter. That could mean both want to respect the impartiality of a coming impeachment trial, where senators effectively serve as a 100-person jury.
But that certainly hasn't stopped Majority Leader Mitch McConnell from saying he's coordinating Trump's own impeachment path with the White House.
It has been cited as a reason for other senators to stay mum. For example, Wisconsin Sen. Tammy Baldwin, a Democrat and the chamber's only other out LGBTQ member, isn't considered by analysts to be in play and is expected to vote for impeachment. But she told WSYR she's honoring an oath for impartial justice. "We have not seen the president put forth any witnesses or evidence to demonstrate his defense, I'm certainly anticipating we will see that," she said.
But as full House and Senate votes loom in Congress on impeachment, Democrats have grown increasingly weary of what it might say if more Democrats than Republicans break ranks on the high-profile votes.