Republican candidates endorsed by Mr Donald Trump won their party's nominations for governor in Pennsylvania and for the US Senate in North Carolina on Tuesday (May 17), underscoring the former president's clout in his party ahead of November's midterm elections.
But Mr Madison Cawthorn, a Mr Trump-backed Republican congressman, lost his bid for a second term after angering party leaders with a dizzying string of self-inflicted scandals.
Pennsylvania state Senator Doug Mastriano, who has amplified Mr Trump's false claims of 2020 voter fraud and marched on the US Capitol on Jan 6, 2021, will face Democratic Attorney-General Josh Shapiro in a governor's race that could have major implications for abortion rights and election integrity.
Some Republican Party insiders feared that Mr Mastriano's primary victory would prove Pyrrhic if he turned off moderate voters in the Nov 8 general election.
Mr Trump has endorsed more than 150 candidates as he tries to solidify his status as his party's kingmaker, though his picks have not always prevailed.
Control of the US Congress - and with it the ability to advance or blockade Democratic President Joe Biden's agenda - is at stake in the midterms.
In Pennsylvania's marquee US Senate race, Lieutenant-Governor John Fetterman - a goateed, tattooed liberal whose fondness for hoodies and shorts has given him everyman appeal - won the Democratic nomination despite having been hospitalised since Friday after suffering a stroke.
Mr Fetterman, a progressive, defeated moderate US Representative Conor Lamb just hours after having had a pacemaker implanted to address the irregular heart rhythms that caused the stroke. He has said doctors expect a full recovery.
His Republican opponent remains to be decided, with another Mr Trump-backed candidate, TV wellness celebrity Mehmet Oz, locked in a tight battle with former hedge fund executive David McCormick.
With 90 per cent of the expected vote reported, Mr Oz was ahead of Mr McCormick by just over 500 ballots out of nearly 1.3 million counted, according to Edison Research. Conservative political commentator Kathy Barnette was far behind in third.
Under Pennsylvania law, any margin of 0.5 per cent or less triggers an automatic recount.
Both Mr Oz and Mr McCormick told supporters late on Tuesday that they expected to win but that a final result was not expected that night, given the number of outstanding mail ballots still to be counted.
"We're not going to have a result tonight," Mr Oz said.
In a statement, Mr Biden praised Mr Fetterman while warning that whoever prevails in the Republican contest "will be too dangerous, too craven, and too extreme" for the state.
In North Carolina, a Mr Trump-endorsed candidate, US Representative Ted Budd, won the state's Republican US Senate nomination.
Mr Budd, who beat former Governor Pat McCrory, will face Democratic former state Chief Justice Cheri Beasley, who is seeking to become the state's first Black senator.
The Pennsylvania and North Carolina Senate races are two of the most important midterm contests, as Democrats fight to retain their slim majorities in the House of Representatives and Senate. Both seats are held by retiring Republicans: Mr Pat Toomey in Pennsylvania and Mr Richard Burr in North Carolina.
Republicans are well positioned to regain control of the House, which could enable them to stonewall Mr Biden's legislative agenda.
Mr Biden's public approval rating is at 42 per cent, with 50 per cent of Americans disapproving of his performance, according to a Reuters/Ipsos opinion poll completed on Tuesday.
Democrats have a better chance of keeping control of the Senate, currently split 50-50 between the parties with Vice-President Kamala Harris holding the tie-breaking vote.
Mr Cawthorn, a staunch Mr Trump ally who at age 26 is the youngest member of the House, conceded his loss to Senator Chuck Edwards, 61, late on Tuesday.
Mr Cawthorn drew criticism from fellow Republicans after a series of embarrassing episodes, including claiming that conservative leaders invited him to a cocaine-fuelled orgy, trying twice to take a gun onto a plane and having a video surface showing him nude and gyrating against someone.
In Pennsylvania, Mr Trump made an 11th-hour endorsement of Mr Mastriano, whose rise worried some establishment Republicans.
Mr Mastriano, who was outside the Capitol on Jan 6, 2021, when a mob of Mr Trump supporters attacked the building, played a significant role in the Trump campaign's failed effort to overturn Pennsylvania's 2020 presidential results based on false claims of voter fraud.
If Mr Mastriano wins in November, he would be able to appoint his own secretary of state, the state's top election official, ahead of the 2024 presidential election, when Mr Trump suggests he may seek a second term in the White House.
Mr Mastriano has also said he would pursue a statewide abortion ban after a leaked draft opinion showed the Supreme Court is poised to overturn its landmark 1973 decision legalising abortion nationwide.
Pennsylvania's Republican-controlled legislature could attempt to pass abortion limits if the court acts, with the state's governor holding the power to sign or veto any new restrictions.
Mr Shapiro, who ran unopposed for the Democratic nomination, has vowed to protect abortion rights. He said on Tuesday that he was isolating at home after testing positive for Covid-19.
Mr Trump's pick for Idaho governor, Lieutenant Governor Janice McGeachin, lost on Tuesday in her bid to oust the incumbent Republican Brad Little. Primary elections also took place on Tuesday in Kentucky and Oregon.