The Rust Belt states that narrowly helped deliver Donald Trump’s presidential victory lost manufacturing jobs in 2019 as trade wars and a strong dollar weighed on business, data showed Friday.

Pennsylvania recorded a drop of about 5,700 factory positions, while Wisconsin lost 4,100 and Michigan was down 5,300, though overall employment increased in those states, according to figures released Friday by the Labor Department.

National numbers previously showed that the U.S. added 46,000 manufacturing jobs in 2019, the second-weakest performance since 2009.

Under pressure from slower demand abroad and the repercussions of the U.S.-China trade war championed by Trump, producers have pulled back on hiring and investment. That may make the road to winning the hearts of voters in manufacturing strongholds like Pennsylvania and Michigan harder in 2020 after Trump vowed to revive the sector.

(Michael Bloomberg is seeking the Democratic presidential nomination. Bloomberg is the founder and majority owner of Bloomberg LP, the parent company of Bloomberg News.)