Detroit — U.S. Sen. Bernie Sanders roared into Michigan on Friday night, using the issue of trade policy as a spear against former Vice President Joe Biden, who's taken the momentum in the race for the Democratic presidential nomination.

Sanders spoke at a rally inside Detroit's TCF Center, kicking off a four-day surge of campaign activity ahead of Michigan's primary election on Tuesday. About 6,000 people attended the event, according to a count from the Detroit fire marshal.

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Sanders slammed Biden on a variety of issues, alleging Biden had been inconsistent on the subject of abortion over his lengthy political career, late to back gay rights and supportive of "disastrous" trade agreements.

"If we are going to defeat Trump in Michigan, Pennsylvania and Wisconsin, it will be very hard for a candidate who voted for these disastrous trade agreements," Sanders told the crowd.

Sanders featured those attack lines in a 48-minute speech, in which he touted his own "100% pro-choice voting record" and his vow to take on Wall Street and the pharmaceutical industry.

Sanders also called for "high quality, affordable child care for every family in America" and promoted his Medicare for All health coverage program, calling health care "a human right."

Before the rally, the Vermont senator participated in a panel discussion on trade policy and highlighted what he described as his "very, very different" record on trade than Biden's.

"I have done my best to oppose these disastrous trade agreements," Sanders said. "Joe Biden, on the other hand, has strongly supported them."

In Michigan, Sanders is trying to win back the momentum in the race for president after Biden won the majority of the 14 states that voted on Tuesday. Sanders pulled an upset in Michigan's primary in 2016, beating Hillary Clinton by 1.4 percentage points.

On Friday, he brushed away Detroit News/WDIV-TV polling that showed him trailing BIden by nearly 7 percentage points in Michigan. Sanders noted that polls showed him behind Clinton ahead of the 2016 primary in the state.

"Polls are polls," Sanders said "All I can say is that we are going to work as hard as we can to win here in Michigan."

But Biden's campaign is trying to deal Sanders a blow in a state that was crucial to him four years ago. Minnesota U.S. Sen. Amy Klobuchar, who was once a candidate for president herself but now supports Biden, made two appearances in the state Friday evening on Biden's behalf.

In an interview inside the MGM Grand Detroit, Klobuchar argued that Biden is the candidate who could put together a coalition of independents, moderates and the Democratic Party's base to "win big" against President Donald Trump.

Klobuchar compared Biden's campaign with Michigan Gov. Gretchen Whitmer's 2018 win. She beat Republican Bill Schuette by 9 percentage points as Democrats also flipped two U.S. House seats in Michigan.

"To do that, you need this big coalition. Biden can lead that coalition," Klobuchar said. "Some of it is an economic check. But a lot of it is a decency check."

Of voters, Klobuchar said, "They are tired of a president that sends mean tweets every morning."

Biden's campaign is sending supporters to Michigan Saturday and Sunday, including former Secretary of State John Kerry. On Monday, Biden will participate in campaign stops in Grand Rapids and Detroit. Details of those events haven't been released yet.

Sanders will hold a Saturday rally in Dearborn and Sunday rallies in Grand Rapids and Ann Arbor. He also will participate in a "town hall on racial and economic justice" at 7 p.m. Saturday at the Mott Community College Event Center in Flint, according to his campaign.

Then, on Monday, he will participate in a Fox News town hall in Detroit. The town hall will be held at 6:30 p.m. at the University of Michigan-Dearborn Field House ice rink. The event is open to the public.

Sanders focuses on trade

Sanders, the Vermont independent, pushed trade policy to center stage during his first Michigan campaign event in the week before the state's primary election on Tuesday.

At a panel discussion inside the TCF Center, Sanders said Detroit used to be the "wealthiest city in the United States" because it had good union jobs.

"We have now transitioned to a situation where Walmart is our largest private employer," Sanders said. "Previously, General Motors in 1960 was our largest private employer. What's the difference between Walmart and General Motors in 1960? Workers in the 1960s earned good wages."

The country's trade policies have "decimated Detroit, Flint and other communities in this state," Sanders said, adding that he and Biden have "very, very different" records on trade.

Biden has supported trade pacts, like the North American Free Trade Agreement, Sanders said. The agreement has cost tens of thousands of jobs in Michigan, Wisconsin and Pennsylvania, Sanders told the crowd. Those three battleground states propelled Trump to victory over Clinton in 2016.

During a debate in January, Biden said he would give environmental and labor leaders a seat at the table to help negotiate trade agreements during his administration. The country needs to focus on equipping American workers for the high-tech economy, Biden said.

"We better figure out how we begin to write the rules of the road, not China," Biden argued of his support of past trade deals.

But Frank Hammer of Detroit said he once represented 3,500 workers at an auto factory in Warren. The factory is now closed, Hammer said. He credited Sanders for his consistency on the subject.

“We think the competition has to be done on a level playing field," Hammer said. "The free trade agreements ensure that it doesn’t.”

Bob King, former president of the United Auto Workers, participated in the panel discussion with Sanders on Friday, King touted Sanders' stances and said he hopes workers "respond" to them.

"I hope young people turn out in Michigan," King said. "They haven't been turning out in other locations as I thought they would. If they turn out in Michigan, he'll do extremely well."

cmauger@detroitnews.com