WASHINGTON — The new Congress convenes Tuesday, and Republicans have a long list of promises to keep. But with a Republican president in Donald J. Trump, they are vowing to end gridlock in Washington. What should you watch for? Here is our cheat sheet.

How quickly will Republicans vote to repeal the health care law?

The majority leader, Senator Mitch McConnell of Kentucky, promised that repeal would be the first order of business. But this does not mean the end of the Affordable Care Act, at least not any time soon.

Republicans will most likely wind their way through a complex process known as budget reconciliation, setting instructions that congressional committees would then have to follow to draft final repeal legislation. And because Republicans have yet to agree on how to replace the law, leaders may postpone for years the effective date for any repeal measure.

How will Democrats handle Mr. Trump’s nominees?

Senate Democrats do not have the votes to block any of the cabinet nominees, though they can slow the process. But absent any major disqualifying revelations, Mr. Trump’s choices are likely to prevail.

Mr. Trump’s choice to replace Justice Antonin Scalia on the Supreme Court could be another matter because Democrats can use a filibuster to try to block the process.

Republicans would need to secure 60 votes for the nominee to be confirmed, more than the 52 that Senate Republicans can manage alone. Mr. McConnell could try to extend the limited prohibition on filibusters to include Supreme Court nominees, lowering the threshold for confirmation to a simple majority.

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