Sen. John Fetterman (D-PA) became the first Democrat in the upper chamber to throw his weight behind Sen. Marco Rubio (R-FL) to be President-elect Donald Trump’s secretary of state.

While top Democrats across the country have already pledged to buck Trump’s White House agenda, Fetterman’s support for the GOP chief’s likely pick to head the State Department signals that he could be one of the few Democrats in the upper chamber willing to work with the next Republican administration.