Can Ruben Gallego Win Over Arizona Swing Voters and Earn a Senate Seat?

As Representative Ruben Gallego campaigned for Arizona’s vital Senate seat last week, he did something that might seem unusual to those who know him as a fierce liberal combatant: He struck a moderate tone.

Speaking to retirees in Goodyear, a politically divided Phoenix suburb, Mr. Gallego, a Democrat, addressed the surge of migrants at the border, suggesting that the asylum system was “being abused” and calling for more support for Border Patrol agents so they could “really focus on those bad guys.”

It was a shift from the Ruben Gallego of years past, when he slammed former President Donald J. Trump’s border wall plans as “stupid” and accused him of “scapegoating immigrants.” The new message — stemming in part from an intensifying crisis under a far different president — represented a tacit acknowledgment that winning over Arizona voters may require a slide toward the middle.

Delicately turning to the political center is a time-honored tradition for candidates of both parties. But Mr. Gallego, who represents a liberal district in Phoenix and has a long history of identifying as a progressive, could face a tougher challenge than most in redefining himself in a battleground state with a decades-old conservative bent — even after a major court decision on abortion this week put Democrats firmly on offense in the state.

“In this era of hyper-partisanship — and there will be national money flooding into Arizona in this Senate race — people will be flinging stereotypes around like crazy,” said Janet Napolitano, a Democrat who served two terms as the state’s governor in the 2000s.

Ms. Napolitano, who noted that Mr. Gallego’s status as a Marine Corps veteran could help him, said that to win statewide as a Democrat, he needed to demonstrate that “you’re there to problem-solve, and you’re there to work hard, and you’re there to represent all Arizonans.”