Americans' frustration with Congress' productivity was palpable before the election. Only 14% of US registered voters approved of lawmakers' performance, an October Gallup poll suggested.

But with a Republican in the White House and Democrats running Congress, Americans may face even more deadlock.

"If you thought legislating was hard in the last Congress with unified Republican control, that will get much more complicated," said Casey Burgat, professor of legislative affairs at George Washington University.

Because they will control both chambers with a comfortable majority, Democrats will be able to pass legislation through Congress with relative ease.

Getting it enacted into law will be harder.

A president must sign most legislation in order for it to become law. Trump has the power to reject legislation passed by Congress that he does not support, and Congress can only override him with a supermajority from both chambers - margins Democrats alone will not have despite their success on Tuesday.

As his party lost Senate race after Senate race Tuesday night, Trump struck a conciliatory tone with the New York Times.

"We'll work with the Democrats, and we'll, you know, look forward to working with them. We'll probably work something out," he said.

But a few minutes later, Trump posted a picture on Truth Social of his red campaign hat with the word "VETO" emblazoned across the front. That Jekyll-and-Hyde approach to a Democratic Congress could become a theme.

While opposition to Trump led to Democrats' success, lawmakers acknowledged Tuesday night, it might not be enough.

"It is overwhelmingly a rejection of Donald Trump, and his agenda and policies," Coons told the BBC.

"But if we overreach, or if we fight too much internally, we could miss this moment."

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