Two congresswomen running for the U.S Senate in Arizona are crisscrossing the state, raising millions of dollars and trying to exploit every possible advantage to win in what both sides expect to be a photo-finish race.
The wild card: Angela Green, a Green Party candidate who could win votes that might have gone to Democrat Krysten Sinema, clearing a path to victory for Republican Martha McSally.
But on Thursday, Green suddenly announced she would drop out of the race and endorsed Sinema.
"After watching the debates and seeing everything, Sinema's stance on a lot of things are very close to mine," Green said in an interview with KPNX-TV in Phoenix.
The about-face demonstrates the significance third-party candidates are playing as Election Day nears and key races tighten across the country. There's a fear that these candidates could become "spoilers" by peeling off just enough support to let the other major party win. Democrats are especially sensitive to the issue after Green Party and Libertarian presidential candidates drew about 5 percent of the popular vote in 2016, the year that Hillary Clinton narrowly lost the presidency to Donald Trump.
"When a race is close everything matters — every demographic group, the number of candidates on the ballot," said Nathan Gonzales, a nonpartisan analyst for Inside Elections. But, he added, that doesn't mean third-party candidates will inevitably tip a close race. "We have to be a bit more nuanced."
Third-party candidates tend to poll better than they actually perform on Election Day, when voters tend to revert to the two major parties. And some who cast ballots for third-party candidates may not otherwise show up to the polls, so it's misleading to presume that every vote for an outside candidate is a vote stolen from a major party.
Regardless, it's a fear present on both sides of the aisle. The biggest impact this cycle may be in Kansas, where Democrats fear businessman and independent gubernatorial candidate Greg Orman, who has notched up to 10 percent support in polls.
Kansas Democrats worry Orman will help Republican Kris Kobach, the chair of Trump's disbanded voter fraud commission, win the governor's race. On Monday, Orman's treasurer, Republican Tim Owens, quit the campaign because he feared Orman was putting at risk the campaign of Democrat Laura Kelly.
"I wish Tim well, but have told him that my campaign is about the people of Kansas, not about establishment figures in Topeka," Orman said, referring to the state capital.
In Georgia, a Libertarian candidate could force one of the nation's most closely watched governor's races into a December runoff.
And in Montana, Sen. Jon Tester has repeatedly won campaigns with less than 50 percent of the vote with a Libertarian candidate on the ballot. This week, an anonymous mailer was circulating that attacked Tester's Republican challenger, Matt Rosendale, and urged a vote for Libertarian Rick Breckenridge.
In response, on Wednesday, Breckenridge said he was endorsing Rosendale. "Matt has the character to combat this, not Jon Tester," Breckenridge said in an interview.
The Montana mailer and endorsement came after an anonymous donor earlier this year bankrolled a drive by a firm that normally works for Republicans to collect 5,000 signatures to place a Green Party candidate on the Senate ballot. Secretary of State Corey Stapleton, a Republican, put the candidate on the ballot, but Montana Democrats successfully sued to overturn it.
In Indiana, similar mailers have circulated attacking Republican Mike Braun and promoting the candidacy of Libertarian Lucy Brenton, who openly says she wants to play the role of spoiler. She garnered 5 percent of the vote in a 2016 race and has been onstage in debates that also include Democratic Sen. Joe Donnelly and Braun. It's unclear which of the two major party candidates is threatened more by her pro-gay rights, pro-marijuana legalization, anti-tax platform.
"Do I intend to spoil the election for them? Absolutely. And here's why: Something doesn't spoil unless it's rotten," Brenton said Tuesday after a debate in Indianapolis. "And the two-party system that has had a stranglehold on our country is absolutely rotten."
Nevada has another option — voters can select "none of these candidates." That helped Sen. Dean Heller win re-election in 2012. Even as then-President Barack Obama handily won the state, Heller was re-elected by an 11,000-vote margin — a total of 46 percent of the vote. That's because 44,000 voters chose "none of these candidates" rather than Heller or his Democratic opponent, Rep. Shelley Berkley, who faced a congressional ethics investigation during the race.
