The Hillary Clinton campaign announced Saturday that the candidate and its top surrogates would deploy in the campaign's final days to Michigan, showing signs of concern amid polls that have shown Republican nominee Donald Trump gaining in the traditionally blue state.

Former President Bill Clinton was set to campaign in Lansing on Sunday, while President Barack Obama will head to Ann Arbor on Monday.

And the Democratic nominee herself will make a swing through the state later Monday in Grand Rapids amid a furious cross-country push in the final hours. She has spent only four days in Michigan since July's Democratic National Convention, far below other swing states like Florida and North Carolina.

"The numbers there have tightened," Clinton campaign manager Robby Mook told reporters Saturday. But he also said the campaign's strategy is to rally supporters at the right time in states like Michigan, Pennsylvania, and New Hampshire, none of which feature early voting.

6 PHOTOS Must-win states for Hillary Clinton See Gallery Must-win states for Hillary Clinton Pennsylvania Hillary Clinton campaigns for President of the United States at University of Pennsylvania on October 22, 2016 in Philadelphia, Pennsylvania. (Photo by Taylor Hill/WireImage) Wisconsin U.S. Democratic presidential candidate Hillary Clinton listens to a question at a campaign event in Madison, Wisconsin, United States, March 28, 2016. (Photo via REUTERS/Jim Young) Michigan Democratic presidential nominee former Secretary of State Hillary Clinton speaks during a campaign rally at Wayne State University on October 10, 2016 in Detroit, Michigan. A day after the second presidential debate in St. Louis, Hillary Clinton is campaigning in Michigan and Ohio. (Photo by Justin Sullivan/Getty Images) Virginia Democratic U.S. presidential candidate Hillary Clinton (C) speaks next to Virginia first lady Dorothy McCauliffe (L) and James Barnett (R) at a discussion on national security during a campaign event at the Virginia Air and Space Center in Hampton, Virginia, U.S., June 15, 2016. (Photo via REUTERS/Gary Cameron) New Hampshire Democratic U.S. presidential nominee Hillary Clinton speaks during a campaign rally at Alumni Hall Courtyard, Saint Anselm College in Manchester, New Hampshire U.S., October 24, 2016. (Photo via REUTERS/Carlos Barria) Minnesota U.S. Democratic Presidential Candidate Hillary Clinton speaks at the American Federation of Teachers conference in Minneapolis, Minnesota, July 18, 2016. (Photo via REUTERS/Adam Bettcher) Up Next See Gallery Discover More Like This HIDE CAPTION SHOW CAPTION of SEE ALL BACK TO SLIDE

Michigan, part of the Democratic "blue wall," has not voted for a Republican candidate since 1988, and Obama won the state in both 2008 and 2012 in comfortable fashion with at least 54% of the vote. But polls there have tightened, along with other battleground states, in recent days. The RealClearPolitics average of surveys in the state gives Clinton a 4-point lead.

On the other side, meanwhile, Trump is set to make a swing through Sterling Heights, Michigan, on Sunday evening. And he will close out his campaign with an 11 p.m. Monday evening rally in Grand Rapids.

Republican vice-presidential nominee Mike Pence has visited Michigan each of the last three days, and he plans to do so two more times Monday, according to the Trump campaign's schedule.

"It's truly remarkable the Clinton campaign is burning their final chip with President Obama by sending him into a state long viewed as deep blue, and this is yet another indication of how strong this movement is boosting Mr. Trump," Trump campaign spokesman Jason Miller told Business Insider.

The Great Lake State has been a thorn in Clinton's side throughout the campaign, as she lost it in shocking fashion to Vermont Sen. Bernie Sanders in the Democratic primary. The state's higher percentage of white, working-class voters fits with Trump's base of support, seen in other Midwestern states like Iowa and Ohio.

Capturing Michigan's 16 electoral votes could open more paths for Trump, who has seen mixed results in swing-state early voting, so far. One top political analyst in the battleground state of Nevada, for example, said Saturday that Trump would need a "miracle" to win the state based on the early-voting numbers.

After the Monday swing through Michigan, Clinton will end her campaign with a midnight rally in Raleigh, North Carolina.

4 PHOTOS Must-win states for Donald Trump See Gallery Must-win states for Donald Trump Florida Republican presidential candidate Donald Trump pumps his fist in the air during a campaign rally at the Collier County Fairgrounds on October 23, 2016 in Naples, Florida. Early voting in Florida in the presidential election begins October 24. (Photo by Joe Raedle/Getty Images) Ohio US Republican presidential candidate Donald Trump speaks at a rally at The Champions Center Expo in Springfield, Ohio, on October 27, 2016. (Photo credit PAUL VERNON/AFP/Getty Images) Iowa Donald Trump, 2016 Republican presidential nominee, speaks during the 2nd annual Roast and Ride hosted by Senator Joni Ernst, a Republican from Iowa, not pictured, in Des Moines, Iowa, U.S., on Saturday, Aug. 27, 2016. Ernst, who in 2014 won the Senate seat vacated by Democrat Tom Harkin when he retired, has turned her Roast and Ride into the conservative answer to the Harkin's legendary Steak Fry fundraiser, which auditioned dozens of presidential candidates over its 37-year history. (Photo by Daniel Acker/Bloomberg via Getty Images) North Carolina Republican presidential candidate Donald Trump speaks to supporters at a rally on September 12, 2016 at U.S. Cellular Center in Asheville, North Carolina. Trump criticized Democratic rival Hillary Clinton for saying that half of his supporters belong in a 'basket of deplorables.' (Photo by Brian Blanco/Getty Images) Up Next See Gallery Discover More Like This HIDE CAPTION SHOW CAPTION of SEE ALL BACK TO SLIDE

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