WARREN, Mich. — With the second round of Democratic debates hours away in Detroit, national party Chairman Tom Perez joined a Michigan congressman Tuesday at a suburban General Motors plant, slated to close, to criticize President Donald Trump’s economic record and promise that the party would take back the critical state of Michigan in 2020.

While no autoworkers attended the event, which pulled in national press in Detroit for the debates, Perez used the impending closure of the Warren Transmission Operations factory, about 20 minutes’ drive north of the city, as evidence of Trump’s failed promises.

In 2016, while campaigning for president, Trump came to Warren and told workers, “If I’m elected, you won’t lose one plant — you’ll have plants coming into this country.”

Last November, GM announced that it would close the Warren plant and several others, prompting scathing rebukes from Trump and Democrats.

For the Democrats, the timing of the closure, on Wednesday, presented an opportunity to challenge Trump at a time when polls show voters have a positive view of the economy.

“We’re here today in this debate today and tomorrow because the difference between the Democratic vision of opportunity for everyone — an America in which we all succeed only when we all succeed — stands in direct contrast to this president’s trail of broken promises,” Perez said.

The Warren plant is located in a county and a state vital in determining who wins the White House.

Macomb County is a longtime working-class swing county that Trump carried by 12 percentage points on his way to winning Michigan narrowly. Macomb voters supported Democrat Barack Obama in 2008 and 2012.

U.S. Rep. Dan Kildee, a Democrat from Flint, appeared with Perez and said Trump gave people in his district “false hope” about the industry. “He cynically plays to people’s anxiety and fear by giving them hope that is not founded on anything and over time, of course that is revealed," Kildee said.

A spokesperson for the Warren Transmission plant said that job transfers were available to other GM locations for all employees, and that 60 of 262 workers have been placed in nearby plants.

Republicans point to Michigan’s low unemployment rate of 4.2 percent among other positive economic indicators.

Democrats at the debate will aim to establish themselves and appeal to voters in a key state. Perez said to expect discussion about universal health care and income inequality. He joked that “hand size,” which became a topic in the Republican primary debate held in March 2016 in the same location, Detroit’s Fox Theater, was unlikely to come up again.

This could be the final debate for some lower-polling candidates unless they can meet increased requirements for the September debate. If more than 10 candidates qualify, the debate will again be held over two nights.

The Detroit area has been a flurry of political activity this week. Colorado Sen. Michael Bennet met with local pipe fitters in Troy on Tuesday. Washington Gov. Jay Inslee used the backdrop of an oil refinery near Detroit to announce a new slate of proposals to combat global warming. Vermont Sen. Bernie Sanders and South Bend Mayor Pete Buttigieg also visited the area in advance of the debate, which will be held over two nights.

Perez said the DNC remains “aggressively neutral” about who should take on Trump.

“Fall in love,” Perez told Democratic voters. “Speed date many people, and then fall in line with our nominee.”