Watch for Trump allies to begin framing Joe Biden as a free-trading globalist who would undo the president's trade agenda.

Why it matters: Trump will try to direct the conversation with his megaphone, and invite attacks on Biden from the left.

Trump allies say that when 2020 candidates to Biden’s left inevitably start hitting him on his free-trade past, Republicans will piggyback to try to undermine him ahead of a potential general election fight in the Rust Belt.

Expect them to begin asking questions like: What specifically will Biden do with China? Will he lift President Trump's tariffs? How does Biden defend his past advocacy for NAFTA and the Trans-Pacific Partnership?

This could be months away, but it's already a hot topic in Trumpworld.

The backdrop: Team Trump is worried about the former vice president.

Internal Trump polls have Biden substantially ahead in the Rust Belt.

The other side: "Trump’s trade war could hit his base of voters most," via CNBC.

Go deeper: Trump’s Biden obsession