Voters mark their ballots at the Central Elementary School during the Ohio primaries on Tuesday in Kent, Ohio.Jeff Swensen/Getty Images
Vivek Ramaswamy, who once advocated building a wall on the Canadian border, will carry the Republican Party’s standard in Ohio’s gubernatorial election, seeking to lead one of the U.S. states most tightly linked economically to the country’s northern neighbour.
U.S. President Donald Trump’s non-stop campaign of revenge, meanwhile, sent a handful of Indiana state senators into early retirement.
These two primary elections this week were just the start of what promises to be a fractious three months as voters decide who will face off in highly competitive midterm elections in November.
In addition to the big political prizes up for grabs – control of the U.S. Senate and House of Representatives, and the governorships of states from California to Michigan – the voting is being marked by a ferocious, Trump-initiated war over gerrymandering and internecine battles for control of both major parties.
Here are six things to know.
What is a primary?
Seven candidates for California governor are participating in the third televised debate, ahead of the June 2, primary elections.FREDERIC J. BROWN/AFP/Getty Images
Unlike in Canada, where nominees for public office are chosen by card-carrying members of political parties (or installed by party leaders), in the United States all voters have a chance to decide which candidates will appear on the general election ballot.
When Americans register to vote, they have the option of indicating which party they usually support. This allows them to vote for who they want that party’s nominees to be. The elections where this happens are called primaries which, unlike November’s general election, are held on different days in different states.
This year, some primaries began in March, with most taking place in May and others happening as late as August.
In some states, voters don’t even have to indicate a political party preference to vote in the primaries: they can show up on primary day and vote in whichever party’s primary they want.
Which major primary races have been decided?
Vivek Ramaswamy speaks during AmericaFest in Phoenix, Arizona, U.S., in December, 2025.Cheney Orr/Reuters
Vivek Ramaswamy, the former pharmaceutical entrepreneur who made a long-shot bid for the 2024 Republican presidential nomination, won his party’s nod this week for Ohio governor with more than 80 per cent of the vote.
Mr. Ramaswamy is primarily known for trying to out-Trump Mr. Trump: during the 2024 race, he vowed to fire 75 per cent of federal government employees and cover the U.S.’s nearly 9,000-kilometre-long northern border with a wall.
It remains to be seen whether such promises – not to mention Mr. Ramaswamy’s bombastic style – can carry him to the governor’s mansion, and whether Ohioans like the idea of cutting ties with their top international trading partner.
In Maine, the primary doesn’t happen until June 9, but the general election Senate matchup already looks set. Graham Platner, an oyster farmer and former Marine running on a leftist platform of universal health care, has proven so popular that he drove the establishment Democrat, Governor Janet Mills, to quit the race.
If Mr. Platner gets the nod, he will face Republican incumbent Susan Collins in what is likely to be the Democrats’ best opportunity to gain a seat in the upper chamber.
Mr. Platner drew national attention last year for sporting a death’s head tattoo that resembles a Nazi SS symbol. He said he and other marines got the tattoo in Croatia without knowing its symbolism. He got it covered with another tattoo when the controversy erupted.
On the other side of the party’s ideological spectrum, North Carolina Democrats this past March nominated moderate former governor Roy Cooper in that state’s senate race. He will face GOP incumbent Michael Whatley in what is also expected to be a competitive race.
Which major primary races are still to come?
Abdul El-Sayed, candidate for U.S. Senate in Michigan, speaks before U.S. Senator Bernie Sanders takes the stage at Mumford High School on May 3, in Detroit, Michigan.Sarah Rice/Getty Images
In Michigan, Abdul El-Sayed is hoping to replicate Mr. Platner’s success in the key swing state’s Aug. 4 Democratic senate primary. The Bernie Sanders-backed former public health official is in a tight, three-way race with moderate Rep. Haley Stevens and state senator Mallory McMorrow, who is aiming to come up the middle
Among the dynamics at play is the support Ms. Stevens has received from pro-Israel group AIPAC – an important factor in a state whose Arab-American community could prove decisive to the result.
On the gubernatorial side, the most intriguing dynamic is outside of the primaries altogether: Mike Duggan, a former Democratic mayor of Detroit, is running as an independent, testing the proposition that the best way to win this evenly-divided state is to court voters of both parties.
California, meanwhile, has an unusual system for its primary on June 2. All candidates of all parties run in a single race and the top two finishers will advance to the general election, regardless of party.
Top-polling contenders are Democrats Xavier Becerra, the former federal health secretary, billionaire Tom Steyer and Rep. Katie Porter; and Republicans Steve Hilton, a British-American TV pundit, and Riverside County Sheriff Chad Bianco.
How does gerrymandering factor in?
Last year, on Mr. Trump’s orders, Texas’s Republican legislature and governor redrew the state’s congressional districts to further gerrymander them. Under the new scheme, five additional seats now lean Republican. This prompted Democrats in California and Virginia to gerrymander their states in a bid to counterbalance Texas’s actions. So, Florida Republicans also got in on the game.
Then, late last month, the U.S. Supreme Court issued a decision effectively allowing Louisiana and other states to eliminate majority-Black congressional districts. Louisiana’s Republican governor, Jeff Landry, suspended the state’s May 16 primary so the legislature can redraw the districts’ boundaries first.
Other Republican-run states, including Alabama, South Carolina and Tennessee, are also looking to rush gerrymanders through as a result.
Usually, the party that holds the White House loses seats in the midterms and with voter anger over affordability issues – exacerbated by Mr. Trump’s war on Iran – the Republicans were looking particularly vulnerable. But the gerrymandering fight could see them come out with more districts newly tilted in their favour than the Democrats.
How does Mr. Trump’s revenge campaign factor in?
U.S. President Donald Trump and Vice-President JD Vance depart after a Military Mother's Day Event in the East Room of the White House in Washington, D.C., on May 6.KENT NISHIMURA/AFP/Getty Images
Speaking of gerrymanders: one Republican-run state that resisted Mr. Trump’s demands to redraw its congressional districts was Indiana. So, the President and MAGA-aligned campaign groups backed primary challenges to seven GOP state senators who refused to comply with his demands.
The US$10-million campaign had its intended effect this week: at least five anti-gerrymandering Republican state senators fell to Mr. Trump’s chosen candidates.
The message is clear. The President’s control over his party remains tight and there will be increasing pressure on other Republican-run states to gerrymander.
Mr. Trump’s retaliation will move to another corner of the country next week, when he is hoping to knock off Bill Cassidy, an incumbent Republican senator in Louisiana. Mr. Cassidy voted to convict Mr. Trump at his second impeachment trial for trying to overturn the results of the 2020 election.
The President is backing one of Mr. Cassidy’s rivals, Rep. Julia Letlow, in a three-way race that also includes John Fleming, the state treasurer. If no one receives a majority, the race will go to a runoff in June.
How else is the Trump effect factoring in?
Two 2020 election-denying members of Congress, Mike Carter and Buddy Collins, are vying for the Georgia Republican Senate nomination against football coach Derek Dooley. Mr. Dooley has the backing of Governor Brian Kemp, who famously refused Mr. Trump’s demand that he help overturn his election loss.
The May 19 primary, which will also go to a runoff if no one achieves a majority, will determine the challenger to Democrat Jon Ossoff, the party’s most vulnerable incumbent senator.
Texas’s Republican primary, meanwhile, has turned into a battle between incumbent John Cornyn and Ken Paxton, the state’s hard-right attorney-general, who has fought to stop women from getting medically-necessary abortions.
A victory for Mr. Paxton in a May 26 runoff could make the state competitive for Democratic nominee James Talarico.