After Pittsburgh and Parkland, Las Vegas and Sutherland Springs, gun control supporters approached Tuesday's midterm election with what they said was more momentum than ever, expecting national frustration with mass shootings to help buoy some candidates to victory.

And on Wednesday, their optimism appeared to be largely affirmed, with victories by gun-control candidates in many of the congressional and gubernatorial races that supporters viewed as referendums on the issue, in states including Pennsylvania, Virginia, and Nevada. But gun-rights supporters touted their own successes, including two U.S. Senate contests and state-level elections in Arkansas, Idaho, and Oklahoma.

The changing tides of the divisive midterm were enough to bring "a gun-sense majority … elected to the U.S. House," said Brynne Craig, political director of Everytown for Gun Safety. That majority is largely aligned with the new Democratic House majority, but gun-control advocates said predictions, based on polling, ad spending, and activism, that gun control would motivate voters were proved correct Tuesday. According to one exit poll by NBC News, most voters said they supported stricter gun laws, with one in 10 naming it as the country's most important issue.

Some key races in Pennsylvania:

Several candidates backed by gun-control groups won congressional elections, including Democrats Chrissy Houlahan in the Sixth District, Susan Wild in the Seventh, and Conor Lamb in the 17th. Houlahan and Lamb, both veterans, had strong backing from the groups and from VoteVets, which teamed up with former Rep. Gabby Giffords' organization to promote "gun sense" candidates. Democrats Madeleine Dean in the Fourth and Mary Gay Scanlon in the Fifth also won.

Rep. Brian Fitzpatrick, a key Republican ally of gun-control advocates, won re-election in the First District. He was one of the few Republicans to receive endorsements from organizations such as Giffords' group and Everytown.

Rep. Scott Perry, a Republican and a staunch gun-rights supporter, won his Dauphin County reelection against Democrat George Scott, a gun-control advocate.

Some key races nationwide:

A major victory for gun-control advocates was the win by Democrat Jennifer Wexton in Virginia's 10th District. Wexton toppled Rep. Barbara Comstock, a Republican backed by the NRA.

Democrat Lucy McBath, whose teenage son was fatally shot in 2012, ran for Congress in Georgia's Sixth District in a bid to reduce gun violence. She declared victory Wednesday afternoon with a slim lead over Rep. Karen Handel, but the race has not been called.

Washington state widely approved a ballot initiative set to make firearm laws there some of the strictest in the country. It was the only state with a firearms-regulation measure on the ballot.

In Nevada, Democrat Steve Sisolak claimed the governorship, succeeding pro-gun-rights Gov. Brian Sandoval, in a state that had the biggest mass shooting in modern U.S. history just over a year ago.

The NRA made gains as the Republicans maintained control of the Senate, with major wins for Marsha Blackburn in Tennessee and Josh Hawley in Missouri.

In Kentucky, Rep. Andy Barr, a Republican with an A-rating by the NRA, kept his seat, fending off veteran Amy McGrath, who had generated buzz from gun-control groups and other progressive organizations.

What’s next

Now, supporters of gun control hope to pass a background-check bill in the House in 2019, which Rep. Nancy Pelosi, the House minority leader, had said would be a top priority if Democrats took the House.

"What we now know for sure is this: The intensity gap on guns has closed. Americans voting with gun violence in mind are voting for gun safety," said Shannon Watts, founder of Moms Demand Action, the grassroots arm of Everytown. "The 2018 election outcomes have marked a new world order. Lawmakers will have to start proving that they're acting to stop gun violence in order to keep their jobs."

Gun-rights supporters, meanwhile, will seek to block votes on bills they view as threatening their freedom or the gun industry.

"You are the most powerful force in American politics, and we will never stop fighting against the anti-gun elitists bent on destroying our Second Amendment freedoms," the NRA tweeted to its members early Wednesday morning.

Gun-control advocates have a list of proposals they'd like Congress to vote on in the next session — measures that the GOP leadership has blocked. Proponents hope a passage of a background-check bill in the House would put significant pressure on the Senate to vote, although that remains unlikely in the Republican-controlled chamber.

Advocates say they also plan to focus on state legislatures, where they hope to pass bills such as one approved last month in Pennsylvania imposing gun restrictions on domestic abusers.

"2018 was, among other things, the year of gun safety," said John Feinblatt, Everytown's president.