WASHINGTON — Advisers to President-elect Donald J. Trump’s transition team, facing complaints from Democrats that they are trying to jam nominees through confirmation hearings, said on Sunday they were confident all the appointees would be approved by the Senate, perhaps even with Democratic support.

Being the minority party, the Democrats would face long odds in trying to derail any of the nominations. They are, however, seeking to delay Republicans’ plans to open hearings on Tuesday until the nominees have completed F.B.I. background checks.

Senator Mitch McConnell of Kentucky, the majority leader, signaled on Sunday that he was unwilling to reschedule any confirmation hearings, which are set to begin with sessions for John F. Kelly, Mr. Trump’s choice to be the secretary of Homeland Security, and for Senator Jeff Sessions of Alabama, the nominee to be attorney general. Five more hearings are scheduled for Wednesday.

Mr. McConnell dismissed the Democrats’ complaints as sour grapes during an appearance on CBS’s “Face the Nation.”