PITTSBURGH (AP) — Vice President Kamala Harris and President Joe Biden are co-headlining a campaign event Monday in the marquee battleground state of Pennsylvania.

Harris, the Democratic presidential nominee, plans to say during the joint campaign appearance in Pittsburgh that U.S. Steel should remain domestically owned — coinciding with the White House’s earlier opposition to the company’s planned sale to Nippon Steel of Japan.

Harris is expected to “stress her commitment to always have the backs of American steel workers,” her campaign says.

That’s similar to Biden, who has said that he opposed U.S. Steel’s would-be sale to Nippon in order to better “maintain strong American steel companies powered by American steel workers.” But it still constitutes a major policy position for the vice president, who has offered relatively few of them since Biden abandoned his reelection bid and endorsed Harris in July.

Both Harris and her Republican opponent, former President Donald Trump, are battling for the union vote. While membership at labor unions has gone down, they could still have a good deal of influence in this election.

In battleground states like Pennsylvania, as well as Michigan, Nevada and Pennsylvania, close to 13% of all workers are union members, according to the Bureau of Labor Statistics.

At the end of July, Harris had 46% of the vote among Pennsylvania union voters compared to Trump’s 50%, according to a poll by Emerson/The Hill. That has since changed in just a month: an August poll shows Harris has 57% of the vote in that demographic, while Trump is down to 42%.