The projection, from data provider DDHQ, would signal that Republicans would hold a majority in both chambers of Congress.
Edison Research has not yet projected House control. It has projected that Republicans will hold at least 214 seats, including two currently held by Democrats, with Democrats holding at least 205, with 16 uncalled. The smallest House majority is 218.
Republicans had already secured a US Senate majority of at least 52-46, Edison Research projected.
During his first presidential term in 2017-2021, Trump's biggest achievement was sweeping tax cuts that are due to expire next year.
That legislation, and Democratic President Joe Biden's signature $US1 trillion ($NZ1.68 trillion) infrastructure law, both came during periods when their parties controlled both chambers of Congress.
By contrast, during the past two years of divided government, Biden has had little success in passing legislation and Congress has struggled to perform its most basic function of providing the money needed to keep the government open.
