DETROIT (MarketWatch) — Donald Trump won Michigan in 2016 by the slimmest of margins. Can he do it again in 2020?

As Democrats prepare to debate each other over two nights in Detroit, polls are pointing to trouble for the president. His net approval in Michigan since taking office is down by 23 points, according to Morning Consult polling. Early surveys have shown Trump is facing stiff competition in the Wolverine State from former Vice President Joe Biden and Sen. Bernie Sanders, and to a lesser extent from Sens. Kamala Harris and Elizabeth Warren.

What’s more, nearly two-thirds of Michigan residents say they haven’t seen an improvement in their households over the past three years, according to a poll of likely 2020 Michigan voters conducted July 17-20 by the Glengariff Group for the Detroit Regional Chamber. In the same survey, 75% said they didn’t see a change or were worse off from Trump’s tax cuts. And most Michiganders believe tariffs hurt the state’s critical auto industry, as well as farmers and consumers.

It’s numbers like these that are giving Democrats an opening in Michigan, where 20 of the party’s presidential contenders will be debating each other Tuesday night and Wednesday night at the Fox Theatre in downtown Detroit.

Voter sentiment “provides a major opportunity for the Democrats to paint Trump as an agent of the wealthy at the expense of the working class,” Tom Ivacko, a public-policy expert at the University of Michigan, told MarketWatch in an email.

Tuesday night’s main attractions will include Sanders and Warren, two progressive senators known for detailed policy prescriptions and personal battles with Trump, who has verbally sparred with each.

Biden takes the stage Wednesday, as does Harris, in what could prove to be a rematch of their brawl in Miami last month. Each debate begins at 8 p.m. Eastern.

Trump was last in Michigan on March 28, when he talked up his tax cuts and told an audience in Grand Rapids, “radical Democrats are the party of high taxes, open borders, late-term abortion, crime, hoaxes and delusions. The Republican Party is the party for all Americans.”

To be sure, Trump and the GOP can point to a declining unemployment rate in Michigan, as well as the addition of manufacturing jobs, since the president took office.

The state’s jobless rate is 4.2%, higher than the national rate of 3.7% but down from 4.9% since he took office in January 2017 — and from double digits in 2011.

And the home of Ford F, -2.25% and General Motors GM, -0.37% has added 18,700 manufacturing jobs since Trump was inaugurated, a modest increase (based on preliminary numbers through June.)

Trump and Republicans can also highlight their tax law. About 65% of American households paid less in individual income taxes in 2018 as a result, according to the Washington-based Tax Policy Center.

Still, Democrats are likely to seize on the scheduled Thursday closure of a GM plant in Warren, Mich., as evidence that the president’s promises to stop job losses in manufacturing are not working. As the Associated Press writes, 265 jobs will be shed.

For Trump and for Democrats alike, the state is critical.

“If Trump loses Michigan, Pennsylvania and Wisconsin, he might fall just short of 270 electoral votes, despite the solid economy,” said Greg Valliere, chief U.S. policy strategist at AGF Investments, in a note on Monday.

Michigan’s Democratic presidential primary is scheduled for March 10, 2020. The state has 16 electoral votes. Trump won Michigan by just 0.2 percentage points in 2016.