Quarterly polling by Republican-founded Firehouse Strategies and 0ptimus finds that President Trump’s lead dropped considerably against both Joe Biden and Bernie Sanders since December in Michigan, Pennsylvania and Wisconsin.

Why it matters: Although Trump leads when matched against Biden or Sanders, his leads against Biden are within the margin of error in each state, signaling a tight contest in those key states if the former vice president wins the nomination.

Of note: In each of the three states, Trump has wider leads in head-to-head matchups against Sanders than against Biden.

Methodology: This survey was conducted on March 5 through 7 and interviewed a total of 1,582 likely 2020 general election voters in Wisconsin (502), Michigan (550), and Pennsylvania (533) via live landline. Margins of error vary by question and segment but is generally ± 4.7% in WI, ± 4.6% in MI, and ± 5.0% in PA for the topline results.

Go deeper: Why Trump is very beatable