Republicans were set to hold a majority of at least 52-48 in the U.S. Senate and added three seats to their 220-212 House of Representatives majority, though with 51 of the 435 races yet uncalled, final control of the lower chamber was yet unclear.
If Republicans ultimately prevail in the House, they would be in a position to dictate the agenda in Washington, helping Trump deliver on his promise to slash taxes and restrict immigration, for at least the next two years until the 2026 midterm elections.
The results also ensured Republicans in the Senate would be able to help Trump appoint conservative judges and other government personnel.
However, Republicans will not secure the 60-vote majority needed to advance most legislation in the chamber.
House majority uncertain
Republicans also won several races that could allow them to expand their 220-212 majority in the House, though the final outcome may not be known for days.
Democrats need to flip at least seven seats to take control of the 435-seat chamber. But their opportunities to do so were gradually diminishing, as Republican incumbents won competitive reelection races in Colorado, Iowa, New Jersey and Virginia.
In Delaware, voters made history by electing Democrat Sarah McBride, the first openly transgender member of Congress.
With at least 200 seats safe for each party, the winning side will likely end up with a narrow majority that could make governing difficult. That has been evident in the past two years as Republican infighting has led to failed votes and leadership turmoil and undercut the party's efforts to cut spending and tighten immigration.
Tight races in the heavily Democratic states of New York and California could determine House control, and California typically takes several days to count its ballots.
