Newsom and Cox traded the lead with about 30 percent each in early returns, with Republican Travis Allen and Democrat Antonio Villaraigosa about 15 points behind them. Will it make a difference?
The stakes are high in California Tuesday as the state's unconventional election system advances the top two finishers, regardless of party affiliation, to face off in November.
California's top-two system can punish a party with too many candidates in one race.
Cox, a business executive, has the GOP's best chance at earning a spot. Diane Feinstein is running for another term.
The expected turnout in San Diego County for Tuesday's June primary election is 40 to 45 percent, according to the San Diego County Registrar of Voters.
National Democrats spent more than $7 million trying to curb and fix the damage inflicted by Democrats attacking each other in districts opened by retiring Republican Reps.
Sensing a Democratic surge, Republican incumbents Ed Royce and Darrell Issa retired, raising Democratic hopes even higher in those races.
And the amount of money being spent on two Democratic primaries for PRC seats is probably unprecedented.More news: Grainy, icy 'dunes' found on Pluto
Polls are closing in New Mexico as voters decide on a Democratic candidate for governor and major-party nominees for two open congressional seats. In 2016, Hillary Clinton won seven of the districts held by House Republicans. Given Van Drew's more moderate profile (he's pro-gun), Inside Elections predicts this is one of the GOP seats that will likely flip.
"As a CEO for a big pharmaceutical company, Bob Hugin made his millions by keeping prescription drug costs high and misleading cancer patients".
"I don't think the Democrats can take the House without New Jersey", said Brigid Harrison, a political science professor at Montclair State University.
"The California suburbs are the center of gravity for voters rejecting Republicans in the era of Trump", said Democratic strategist Jesse Ferguson.
The names of registered voters are included on lists poll workers use to record who votes.
The number of electoral districts in Ontario has increased from 107 to 124 in 2018 and the change means some voters will be casting ballots in different locations or electoral districts in this election than previously, Elections Ontario said.
Republicans hold five of New Jersey's 12 congressional seats.
Tuesday afternoon, Fox said she had returned to the precinct and voted. Fellow Democrat Fiona Ma, a member of the state Board of Equalization, is also on the ballot, along with Republicans Greg Conlon and Jack Guerrero and Peace and Freedom candidate Kevin Akin.More news: Immune treatment cured my terminal breast cancer
Democratic voters, undeterred by a federal corruption case U.S. Sen. Jon Tester, who is among the most vulnerable Democratic senators in the nation. State Auditor Matt Rosendale and former judge Russ Fagg are the top contenders for the GOP nomination.
Democrats have aimed their most aggressive attacks at Rosendale, seizing on his background in Maryland and questions about his experience as a rancher.
Primary victories by Menendez and former Celgene Corp. chief executive Bob Hugin set the stage for New Jersey's only statewide race in November as President Donald Trump and national Republicans defend a narrowly divided Senate.
Republican New Jersey Assemblyman Jay Webber has won his party's primary in the 11th Congressional District.
In Alabama, four-term Republican Republican Martha Roby was forced into a run-off election next month after failing to win 50 per cent of her party's vote.
The race is sure to garner attention from outside the state because control of the U.S. Senate is up for grabs.
California's outcomes probably won't be decided Tuesday because the state allows mail-in ballots to be postmarked through primary day.More news: Amid growing spat with Facebook, Apple increases privacy controls