President Barack Obama smiles as he arrives to speak at a campaign rally for Democratic presidential candidate Hillary Clinton, Thursday, Nov. 3, 2016, at the University of North Florida in Jacksonville, Fla. (AP Photo/Pablo Martinez Monsivais)

WASHINGTON - Hillary Clinton is rushing to secure Michigan and bolster the Democrats' vaunted blue wall of upper Midwestern states that have backed the party's presidential nominee for two decades, sending in reinforcements as Donald Trump aims to blow up the former secretary of state's path to 270 electoral votes.

Clinton on Friday planned to rally Democrats in Detroit, where a large turnout of black voters have long been crucial to success, following up on a last-minute meeting by former President Bill Clinton with black ministers on Wednesday night.

Clinton's campaign has noted that both Michigan and Pennsylvania do not have in-person early voting, requiring them to intensify turnout efforts in the days leading up to Tuesday's election. But the late focus on Michigan, which has not received extensive attention from Clinton during the campaign, underscored Democratic concerns that Trump was gaining in a state that hasn't backed a Republican presidential candidate since 1988.

Trailing in several battleground states, Trump's fortunes have improved since FBI Director James Comey's stunning announcement that the bureau was looking into emails that may be related to the investigation into Clinton's use of a private server.

The GOP nominee still faces a treacherous path to the White House. Given the current state of the political map, even victories in ultra swing states like Ohio and Florida would not guarantee Trump the presidency. In order to overtake Clinton, Trump would need to win several battleground states if he fails to pick off a blue-collar state like Pennsylvania, Michigan and Wisconsin. Combined, those three states account for 46 electoral votes.

But if Trump managed to win one of these states, it opens more pathways for him to overtake Clinton, who would need to rely more heavily on swing states. In addition to Detroit, Clinton was campaigning Friday in Pittsburgh and Cleveland while Trump planned a campaign stop in Hershey, Pennsylvania on Friday night.

In a sign of the urgency, the candidates and outside groups have shuffled advertising money in the final few days to emphasize Pennsylvania, New Hampshire and Michigan — places with only same-day voting.

Clinton and the main super PAC helping her are spending at least $8 million in Pennsylvania, while Trump and super PACs aiding him have about $2.5 million on the air. In Michigan, a state that had seen no major advertising during the general election, both candidates' buys are approaching $1 million.

Clinton's team roughly doubles Trump's ad spending this week in New Hampshire.

In Detroit, Bill Clinton met privately with black ministers, community leaders, members of the state's congressional delegation and the city's Democratic mayor, Mike Duggan, "to galvanize support for Hillary and Democrats up and down the ballot," Clinton's campaign said.

Voter turnout in Detroit, especially among African-Americans, is pivotal to Democrats in the state. Detroit's metropolitan region typically accounts for nearly half of the Democratic vote in statewide elections. While Obama carried Michigan by comfortable margins in both 2008 and 2012, polls have shown Clinton with a single-digit lead over Trump.

Hillary Clinton's trip to Michigan will be the latest by a Democratic nominee since 2004, when John Kerry visited Detroit the day before the election. Kerry won the state by 3 percentage points. In his two campaigns, President Barack Obama easily carried Michigan twice, by 16 points in 2008 and nearly 10 points in 2012.

Republicans said the race has tightened in suburban Detroit, especially Oakland County, home to thousands of traditional Republicans, and Macomb County, home to working-class white voters who were known as "Reagan Democrats" in the 1980s.

"Michigan is definitely in play," said Dan Pero, chief of staff to former Michigan Gov. John Engler, a Republican. "You began to see Republican movement this week. And the Trump message plays very well in rural and working-class Michigan. We're seeing state numbers showing the race in low single digits."

The race was never expected to be a landslide, said Amy Chapman, a senior adviser to Obama's two statewide races. Clinton has advertised very little in Michigan, but has revived her ad campaign, as any campaign with the fundraising advantage the Democratic nominee would, Chapman said.

"They wouldn't put all the resources into the state that they have," Chapman said, referring to the staff Clinton has assembled there. "You don't do that in a state where you don't think you're going to have to run a robust campaign."

__

Beaumont reported from Prole, Iowa. Associated Press writers David Eggert in Lansing, Michigan, and Julie Bykowicz in Washington contributed to this report.

News from © The Associated Press, 2016