Democratic Sen. John Fetterman of Pennsylvania is expected to deliver a video message at the Republican convention, according to people familiar with the matter, an extraordinary move that will spur more speculation about the lawmaker's political future.

Fetterman is expected to introduce fellow Pennsylvania Sen. David McCormick, a Republican, in the video. The two senators have formed a close bipartisan relationship.

In particular Fetterman is expected to praise the Trump administration's efforts to help the steel industry in his state, according to a person familiar with the message. He is also expected to distance himself from the left wing of the Democratic Party, which has gained momentum in primary elections this year.

The planned video was earlier reported by Axios. Fetterman's popularity among Democratic voters has plummeted due to his sharp defense of Israel, sparking speculation he might switch parties.

In May, Fetterman publicly denied he is considering such a move. But he has left open the possibility he could feel the need to leave the Democratic Party, if it adopts language in its platform that he believes is anti-Israel.