After Cold Shoulders for Biden, Senate Democrats Wrap Their Arms Around Harris

When President Biden campaigned in Michigan last month, Representative Elissa Slotkin, the Democrats’ nominee for the state’s open Senate seat, was nowhere to be found. But on Wednesday night, just weeks after that no-show, Ms. Slotkin announced her full-throated support for her party’s new presidential ticket at a Detroit rally.

Appearing in front of an estimated 15,000 people at the rally for Vice President Kamala Harris and her newly minted running mate, Gov. Tim Walz of Minnesota, Ms. Slotkin concluded her speech by delivering her final punch at the Republicans’ vice-presidential nominee, Senator JD Vance of Ohio.

“Let me just say one thing again about Midwestern values, and again you’re going to have to excuse me: No red-blooded Michigander is ever going to let a Buckeye get into the damned White House,” she said.

Ms. Slotkin is not alone in recognizing the new political landscape since Mr. Biden decided to end his re-election bid. The new energy and rapid coalescing of Democrats behind Ms. Harris and Mr. Walz have drastically changed the strategies of both Democrats and Republicans alike in down-ballot races.

Gone are the days when Democratic candidates for the House and the Senate conveniently pleaded prior engagements during visits from their standard-bearer as they quietly issued calls for him to step aside. Gone also are Republican hopes for a collapse in Democratic turnout from a demoralized base that would mean an easy Republican takeover of the Senate and a healthy expansion of the party’s narrow majority in the House.

New polling from The New York Times and Siena College shows narrow leads for Ms. Harris among likely voters in the crucial battleground states of Pennsylvania, Michigan and Wisconsin — but far bigger leads for down-ballot Democratic candidates.