Texas Rep. Joaquin Castro (D.) predicted a "very strong wave" in 2018 for Democrats on Wednesday in the wake of a hugely successful 2017 election night for his party.
The most watched race was for Virginia governor, where Ralph Northam (D.) scored a surprisingly lopsided, nine-point win over Republican Ed Gillespie, the most lopsided victory for a Democrat in that contest in decades.
Democrats also made significant gains in the Virginia House of Delegates and could potentially win a majority there.
Democrat Phil Murphy rolled to a win in the gubernatorial race in New Jersey as well, and Democrats also made local race pick-ups around the country in the party's most successful election night since 2012.
Castro and other Democrats are viewing the results as a repudiation of President Donald Trump, who has historically low approval ratings for a president less than a year into his tenure.
"I think it's clear that Donald Trump has been toxic for the Republican Party so far," Castro said on MSNBC. "Whatever Midas Touch the president had in the 2016 elections didn't carry over to many elected officials or politicians in his party, and it's not uncommon.
"We've seen that in many midterms where a president's party gets beaten very badly, but this looks like a very strong wave getting ready for 2018."
Democrats are in the minority in both houses of Congress. They have been in the minority in the Senate since losing in 2014, and they haven't held the majority in the House of Representatives since the Republican Tea Party wave in 2010.