May 17 will mark the single busiest primary day to date this year, as voters in several states head to the polls to cast their ballots in some of the cycle's biggest nominating contests.
At stake are hotly contested Senate nominations in crucial battlegrounds like Pennsylvania and North Carolina. The primaries will also be the latest test of former President Donald Trump's sway over GOP voters as he weighs another bid for the White House in 2024.
Here are seven races to watch on Tuesday:
Pennsylvania's GOP Senate primary
The Republican race for the nomination to succeed retiring Sen. Pat Toomey (R-Pa.) is set to test whether Trump's endorsement will be enough to propel celebrity physician Mehmet Oz, a first-time candidate and relatively recent arrival to Pennsylvania, over the finish line.
Public polling in recent weeks suggests that it just might be. Oz has carried narrow, single-digit leads over his nearest rivals since notching Trump's endorsement in early April.
Still, those polling leads, which range from just 1 to 3 percentage points, suggest that Oz is far from a shoo-in and the race isn't immune to last-minute surprises. For much of the past month, former hedge fund CEO David McCormick trailed Oz in a close second place. But another candidate, conservative commentator Kathy Barnette, has surged in the final weeks of the primary, overtaking McCormick for the No. 2 spot.
She's also getting some last-minute help from the conservative Club for Growth, which endorsed her this week and is spending some $2 million on TV ads seeking to boost her candidacy in the closing days of the nominating contest.
Pennsylvania's Democratic Senate primary
On the Democratic side, the Senate primary has emerged as something of a proxy battle between the party's moderate and liberal wings, with Pennsylvania Lt. Gov John Fetterman occupying a more progressive lane and Rep. Conor Lamb (D-Pa.) campaigning as a pragmatic legislator.
Fetterman is seen as the clear favorite in the primary. He's carried wide, double-digit leads in polling for months and just recently passed the 50-percent mark in a Franklin & Marshall College survey released earlier this month.
Still, Lamb has sought to make the argument that Fetterman is too progressive to win the November general election in a state that President Biden carried by just over 1 percentage point in 2020 - especially in a midterm election year that's already expected to be a punishing one for Democrats.
But Fetterman still has a lot going for him heading into the primary. Not only is he the clear frontrunner, but he has aggressively courted the state's Democratic base and used that popularity to build a fundraising juggernaut that could prove particularly useful in a general election campaign.
Pennsylvania's GOP gubernatorial primary
Pennsylvania Republicans appeared poised to nominate state Sen. Doug Mastriano on Tuesday to take on Democrat Josh Shapiro in the November general election, stirring concern among some GOP officials who fear that Mastriano may prove unelectable.
Recent polling in the race shows Mastriano leading the rest of the Republican field by double-digit margins, with one Fox News survey from earlier this month showing him leading former Rep. Lou Barletta (R-Pa.) in the primary 29 percent to 17 percent.
Mastriano has carved out a lane in the race as a far-right adherent of Trump's baseless claim that the 2020 election was tainted by widespread voter fraud and malfeasance. He was subpoenaed earlier this year by the House select committee investigating the Jan. 6 riot at the U.S. Capitol for his alleged role in Trump's effort to overturn the results of the last presidential election.
Shapiro, meanwhile, isn't facing any primary challengers and has the unified support of his party, potentially giving him a leg up in the general election, especially if Republicans are unable to coalesce around their eventual nominee.
North Carolina's GOP Senate primary
Former North Carolina Gov. Pat McCrory once looked like the candidate to beat in the primary to succeed retiring Sen. Richard Burr (R-N.C.). But in the nearly year-long period since Trump endorsed Rep. Ted Budd (R-N.C.) in the race, North Carolina Republicans have coalesced around his candidacy, making him the favorite to clinch the nomination on Tuesday.
Since early April, Budd has racked up double-digit leads in public polling, with an early May survey from The Hill and Emerson College showing him notching a 27-point advantage over McCrory, who has suffered repeated attacks from Trump, including accusations that he's a "RINO," or Republican in name only.
Beyond Trump's endorsement, Budd has also benefited from heavy spending by the Club for Growth, which is pouring some $15 million into the race to boost the three-term congressman.
The recent poll from The Hill and Emerson College also found that Budd is the GOP candidate best positioned to take on the likely Democratic Senate nominee Cheri Beasley in November; in a hypothetical head-to-head matchup, Budd led Beasley 48 percent to 41 percent.
North Carolina's 11th District GOP primary
Rep. Madison Cawthorn (R-N.C.) has stirred controversy after controversy since entering the House in early 2021. Now he's locked in a fight for his political survival.
Cawthorn is facing a crowded field of primary challengers in his western North Carolina district, many of whom jumped into the race after he decided to run in another district closer to Charlotte. Cawthorn returned to his old district, however, after state courts struck down North Carolina's new House map.
Things have only gotten more difficult for him since then. The top Republicans in the state General Assembly have endorsed one of his rivals, state Sen. Chuck Edwards, as has Sen. Thom Tillis (R-N.C.). Burr has also criticized Cawthorn publicly, calling him an "embarrassment" during a March appearance on CNN.
The controversies have also continued to snowball for Cawthorn. He angered many of his fellow House Republicans after he suggested that his colleagues had invited him to orgies and do cocaine. He has also been the subject of a series of salacious revelations, including a leaked nude video.
Still, he has the endorsement of Trump, turning the race into just one more test of the former president's influence.
Oregon's 5th District Democratic primary
Progressives are pushing aggressively to knock off moderate Rep. Kurt Schrader (D-Ore.), who's facing a challenge next week from Jamie McLeod-Skinner in a primary that could become one of the year's major battles between competing factions of the Democratic Party.
The nominating contest in Oregon's 5th District has already attracted the attention of the party's most influential figures. Top progressives like Sen. Elizabeth Warren (D-Mass.) have come out in support of McLeod-Skinner.
Meanwhile, Biden endorsed Schrader last month, frustrating many progressives who see him as an unreliable Democratic vote in the House. Moderates worry that if Schrader loses the primary, it could cost the party his seat in November, especially given that Republicans are expected to target the seat aggressively this year.
Idaho's GOP gubernatorial primary
Incumbent Gov. Brad Little is staring down a primary challenge from Trump-backed Lt. Gov. Janice McGeachin, making him one of only two sitting Republican governors whom the former president is opposing this year.
Little hasn't drawn Trump's ridicule like Georgia Gov. Brian Kemp, the only other incumbent GOP governor whom the former president is campaigning against. But Trump's decision to back McGeachin threw a curveball into the primary.
Little and McGeachin have long had an antagonistic relationship with one another, especially when it comes to the coronavirus pandemic. On more than one occasion when Little has left the state, McGeachin has used her authority as acting governor to sign executive orders, many of which were related to the Covid-19 outbreak, only to have them repealed by Little shortly thereafter.
Of course, Little isn't exactly a moderate. But McGeachin is still challenging him from his right. Not only has she broken with him on his handling of the coronavirus pandemic, but she was among Trump's earliest supporters during his 2016 presidential bid.
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