In most battlegrounds, Biden has a major advantage over Trump among women. But in Arizona, the two are in a tight race for that key demographic. The president and his party have steadily lost ground since 2018 as white, college-educated women have abandoned him.

McCain could help push those who are still undecided into Biden’s corner.

Those women are “definitely an audience that Cindy McCain appeals to,” said Paul Bentz, a Republican pollster in the state.

“Trump’s team should be most troubled by that female gap and how challenged they are particularly among some of those groups,” Bentz said. “Among the 300,000 or so likely swing voters that we’re going to see in this election, it makes a big difference to have the representative of our longtime and very popular United States senator side with Biden.”