Slotkin and Rogers, long considered the front-runners for their respective party nominations, will now shift focus to the general election. Slotkin enters with a massive fundraising advantage and emerges nearly unscathed from a sparse primary, while Rogers has the backing of national Republican groups and former President Donald Trump.

Slotkin defeated actor Hill Harper in the Democratic primary, while Republicans chose Rogers over former U.S. Rep. Justin Amash and physician Sherry O'Donnell. Both candidates will now compete for a seat left open by longtime Democratic Sen. Debbie Stabenow's retirement.

The retiring incumbent quickly endorsed Slotkin after the race was called by The Associated Press, saying on social media that she was "excited to pass the torch at the end of the year." No Republican has won a U.S. Senate race in Michigan since 1994.

With Democrats holding a razor-thin majority in the Senate and Republicans in the House, competitive races like those in Michigan are drawing lots of attention. The state's status as a key presidential swing state raises the stakes for those seats even higher, with party control on the line from the top of the ballot all the way down to the state Legislature.

Michigan's open Senate seat is one of a handful of races nationwide that will determine control of the upper chamber in November. With a later congressional primary, Slotkin and Rogers will have a short period to transition from competing against their own party members to appealing to a broader base of voters for the Nov. 5 general election, which may explain why they have campaigned with their eyes on the general election.

National groups on both sides have already reserved millions for advertisements after the primary. Both Slotkin and Rogers, viewed for months as the overwhelming favorites in their primaries, have skipped debates and refrained from holding large campaign events.

Several U.S. House seats with primaries on Tuesday could influence the balance of power in the lower chamber, but there, too, the biggest battles will be fought in the fall campaign.

Slotkin's entry into the Senate race has left her mid-Michigan 7th Congressional District seat open, historically one of the nation's top battleground districts. Both party candidates are running unopposed in their primaries there, setting the table for a November matchup between Democrat Curtis Hertel Jr. and Republican Tom Barrett.

The 8th Congressional District is also an open race with U.S. Rep. Dan Kildee's retirement. The Democratic congressman has endorsed state Sen. Kristen McDonald Rivet to take his place, but state Board of Education President Pamela Pugh and Matt Collier, the former mayor of Flint, are also vying for the party's nomination.

On the Republican side, former TV anchor Paul Junge is making another bid after losing to Kildee by over 10 percentage points last year. Joining him in the race are Mary Draves, a former chemical manufacturing executive at Dow Inc., and Anthony Hudson.

Meanwhile, several incumbents in battleground seats are waiting to see who they will face in November.

U.S. Rep. Hillary Scholten, who in 2022 became the first Democrat to represent Grand Rapids in decades, is awaiting the outcome of the Republican primary between attorney Paul Hudson and businessman Michael Markey Jr. in the western Michigan district.

National Democrats are also hoping to flip a district just north of Detroit currently held by freshman GOP Rep. John James. Carl Marlinga, a longtime Macomb County prosecutor who lost to James in 2022 by 1,600 votes, is facing Emily Busch, Tiffany Tilley and Diane Young in the Democratic primary.

In a heavily Democratic district encompassing downtown Detroit, U.S. Rep. Shri Thanedar faces a challenge from Detroit City Council member Mary Waters, who is endorsed by Mayor Mike Duggan. Thanedar has significantly outraised her and is favored to win the Democratic nomination, which would likely leave Detroit -- a city that is nearly 80% Black -- without Black representation in Congress for a second consecutive term.

Down-ballot races are holding primaries across the state on Tuesday. Control of the state House of Representatives will be at stake in November, with all 110 seats up for election. Democrats took control of both chambers and the governor's office for the first time in four decades in 2022 and will be trying to defend those majorities.

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Associated Press writer Isabella Volmert in Lansing, Michigan, contributed to this report.