Ms. Slotkin, a former C.I.A. analyst who represents a divided district, is expected to focus heavily on economic matters.Representative Elissa Slotkin, a Michigan Democrat and former C.I.A. analyst who has notched several high-profile victories in a challenging district, said Monday that she would run for the Senate seat being vacated by Senator Debbie Stabenow, a Democrat.Ms. Slotkin is the first Democrat running in what could be a hotly contested primary followed by a marquee fight in the general election, held during a presidential year in a major battleground state.“We need a new generation of leaders that thinks differently, works harder and never forgets that we are public servants,” Ms. Slotkin said in an announcement video released Monday morning.In Michigan, an industrial Midwestern state that helped propel Donald J. Trump to the White House in 2016 before narrowly flipping back to the Democrats in 2020, Ms. Slotkin is planning a pitch heavily focused on jobs and economic matters. An adviser, granted anonymity to discuss internal strategy, said to expect a campaign message that emphasized American manufacturing, “jobs with dignity” and labor protections.“We seem to be living crisis to crisis,” Ms. Slotkin said in the video. “But there are certain things that should be really simple, like living a middle-class life in the state that invented the middle class.”She also stressed the importance of “preserving our rights and our democracy so that our kids can live their version of the American dream.”There have been two school shootings in Ms. Slotkin’s district over the last 15 months, including one at Michigan State University this month. She is expected to focus on issues of safety, especially combating gun violence, the adviser said.Politics Across the United StatesFrom the halls of government to the campaign trail, here’s a look at the political landscape in America.In New York: The state almost single-handedly cost Democrats their House majority in the midterms. Now, a leading Democratic group is hoping New York can deliver the party back to power.Blue-Collar Struggles: A new report from Democratic strategists found that the economy was a bigger problem than cultural issues for the party in the industrial Midwest. It also found hopeful signs for Democrats.Black Mayors: The Black mayors of New York City, Los Angeles, Chicago and Houston have banded together as they confront violent crime, homelessness and other similar challenges.Wisconsin Supreme Court: Democratic turnout was high in the primary for the swing seat on the court, ahead of a general election that will decide the future of abortion rights and gerrymandered maps in the state.Ms. Slotkin, an experienced fund-raiser who represents a Lansing-area district that includes plenty of Republican voters, has impressed state and national Democrats with her electoral track record. She flipped a Republican-held district in 2018, held it in 2020 and was widely seen as endangered last fall, but ultimately won by five percentage points.And in a nod to her focus on bipartisanship, she featured images of former Presidents George W. Bush and Barack Obama in her biography-heavy announcement video as she noted that she had worked “in the White House under two presidents, one Republican and one Democrat.”Her relatively moderate politics, a boon in her House district, may be viewed skeptically by more progressive voters and activists across the state who could mobilize in a primary. There is already public and private clamoring in some quarters for a more robust and diverse primary field, even as a number of the state’s most high-profile Democrats have passed on runs themselves.Ms. Slotkin, for her part, emphasized in a tweet on Monday that “I’ve never taken corporate PAC money, and I’m not starting now.”Ms. Slotkin will also need to introduce herself to Black communities in a number of the state’s bigger cities. She is planning to visit cities including Detroit, Grand Rapids and Flint soon, the adviser said on Friday.The state primary is not expected to be until August of next year, and it is not yet clear what the final field may look like, or how competitive it may ultimately be.A number of the state’s most prominent politicians — including Gov. Gretchen Whitmer, Mayor Mike Duggan of Detroit and Representative Haley Stevens — have indicated they do not intend to run. Pete Buttigieg, the U.S. transportation secretary whose official residence is now in Michigan, has said the same.On Friday, State Senator Mallory McMorrow, a prominent lawmaker who went viral last year defending L.G.B.T.Q. rights, also said she would not run.Many elected officials and other power players in the state had been waiting to see whether Garlin Gilchrist II, the state’s first Black lieutenant governor, would jump into the race, and some had wanted to support him. But on Sunday, he wrote on Twitter: “Serving our state in Washington, D.C. would be a great opportunity, but instead I will keep standing tall for Michigan, right here at home, as Lieutenant Governor. The Governor & I have more work to do. I look forward to working with our next US Senator to get it done.”Some Michigan Democrats have emphasized the importance of Black representation in the primary.“Michigan has this rich pool of qualified African American candidates, and we have so few that represent us in the Senate,” former Representative Brenda L. Lawrence, Democrat of Michigan, said in an interview on Friday. “We have an opportunity to send a qualified public servant to the Senate, so I just really think it’s important. And I think Michigan has the opportunity to fulfill that.”She pointed at the time to Mr. Gilchrist and Hill Harper, an actor in the TV series “The Good Doctor,” as potentially strong candidates. She also said she had not “shut the door yet” on her own potential bid.And there is renewed attention to the intentions of Michigan’s secretary of state, Jocelyn Benson. She has not ruled out a bid, but previously signaled she was more focused on her current job.Representative Debbie Dingell has not categorically ruled out a run, either.Republicans haven’t yet landed their own high-profile candidate. Nikki Snyder, a Republican member of the state board of education, was the first to jump in. But Representative John James, Michigan’s first Black Republican member of Congress, indicated on Friday that he would not seek the seat.Former Representative Peter Meijer, who lost his primary after voting to impeach Mr. Trump, is perhaps the most prominent potential Republican contender, although he would have clear difficulties navigating another primary.Others who either have indicated interest in running or are often mentioned in Republican circles include Representative Lisa McClain; State Senator Ruth Johnson; Kevin Rinke, who lost a largely self-funded Republican primary campaign for governor last year; and former Representative Mike Rogers.The National Republican Senatorial Committee has previously pledged to “aggressively target this seat.” In a statement on Monday, Maggie Abboud, a committee spokeswoman, called Ms. Slotkin a “liberal politician.”Democrats are betting that, as the Michigan Republican Party moves further to the right — it is now helmed by an election-denying Trump acolyte — the strongest potential general election contenders, like Mr. Meijer, would struggle to make it through a primary, paving the way for a far-right nominee who would face significant challenges in a general election.But many have warned that the strong Democratic showing in the midterms in Michigan — against a number of right-wing Republicans — should not be mistaken for a tidal shift in the state’s highly competitive politics.“I don’t know that the state itself has swung more Democratic,” Mr. Duggan said. “I think it has more to do with the caliber of leaders that we’ve had in recent years.”“This state,” he added, “is very closely divided.” More