Tuesday marks one of the most closely-watched election days before November's midterm elections as Alabama, California, Iowa, Mississippi, Montana, New Jersey, New Mexico and South Dakota hold major primaries.

Follow primary election live updates below:

California primary results: Gavin Newsom, John Cox advance

Democrat Gavin Newsom, Republican John Cox advance to November

California's House, Senate and gubernatorial primaries on Tuesday are being dubbed a "jungle primary," or a nonpartisan blanket primary as it's more formally known. It puts all candidates together in one big primary regardless of what party they belong to.

Democratic Lt. Gov. Gavin Newsom and Republican John Cox will both advance to the ballot in the gubernatorial race come November, according to the Associated Press.

"Thanks to you, the halftime score is looking very promising," Newsom said as he took the stage, adding it was "not a victory speech."

Newsom and Cox bested Republican Travis Allen, Democrat Antonio Villaraigosa and Democrat John Chiang, among others in the crowded gubernatorial race.

• Democratic Sen. Dianne Feinstein did take first place in her party's California primary, according to the AP, advancing to the general election for a possible fifth full term.
• House Minority Leader and Democrat Nancy Pelosi will also advance to November, the AP projected.
• Both top members of the House Intelligence Committee, GOP Rep. Devin Nunes and Democratic Rep. Adam Schiff, will also advance to November.

But the California races might not all be decided Tuesday night, or even Wednesday morning -- in California, anyone can vote by mail, and most do. As long as the ballot is postmarked by Tuesday, the vote is valid. In some close contests, those votes could be deciding factors. Polls closed at 11 p.m. EDT.

"Random issue" leaves more than 100,000 voters off in L.A.

California's primaries are arguably the most-watched of Tuesday night. But a snafu has already complicated the state's complicated election night.

Los Angeles County Registrar-Recorder Dean Logan told CBS Los Angeles voters whose names did not appear on the roster at their polling place would be given provisional ballots, after a printing issue affected the voter rolls of more than one in four precincts. A total of 118,522 names were omitted.

Congress

California is of particular importance to the Democrats in their quest to take back the House. In 2016, Hillary Clinton won seven of the districts held by House Republicans. The Democrats have their sights set on turning as many of these seats blue as possible. A number of Republicans in California aren't returning to Congress after 2018, leaving their seats as possible pick-ups for Democrats.

President Trump tweeted his support of California Republicans House Majority Leader Kevin McCarthy as well as Nunes. The AP projected after midnight that McCarthy will win the GOP nomination.

Christina Bellantoni, assistant managing editor for politics at the Los Angeles Times, told CBSN that in California, "You've seen the Democratic Congressional Committee actually spend to...prop up Republicans."

One key race is in the 48th Congressional District, currently represented by Republican Rep. Dana Rohrabacher. As of midnight, he still had the most votes, followed by a close third between Democrat Hans Keirstead and Republican Scott Baugh.

"I was out talking to voters in Huntington Beach, which is Dana Rohrabacher's 48th Congressional District," Bellantoni said. "Many people didn't even know who he was. Somebody told me he thought 'she' was doing a really good job in Congress."

South Dakota primary results

The AP projected Rep. Kristi Noem has won the GOP primary against state Attorney General Marty Jackley, in her bid to become governor. Noem will advance to the ballot in November in the heavily Republican state. The AP projects she will run against Billie Sutton, presumed Democratic nominee for governor.

New Mexico primary results

The AP has called the Republican race for Senate for Mick Rich. The AP also called the Democratic nomination for Senate in favor of Martin Heinrich.

In the gubernatorial contest, the AP projected that Rep. Michelle Lujan Grisham will win the Democratic primary. If she wins in the fall, she would take over from another Hispanic female governor, Susana Martinez, who is term limited.

The AP also projected Debra Haaland to win the Democratic nomination in the state's 1st congressional district.

The polls in New Mexico closed at 9 p.m. ET.

Iowa primary results

The AP called the Iowa Democratic primary for retired Des Moines businessman Fred Hubbell. He will face Republican Gov. Kim Reynolds come November. Election officials, according to the AP, said the race appeared to have record turnout.

CBS News ranks Iowa's Republican-held third congressional district, which stretches from Des Moines to the Nebraska border, as probably competitive as the Democrats hope to unseat Republican incumbent David Young.

Montana primary results

Republican Montana voters will determine who will challenge incumbent Democratic Sen. Jon Tester this fall -- state auditor Matthew Rosendale or former Yellowstone County District Judge Russell Fagg.

Republican primary hopefuls vying to take on Tester are aligning themselves with Mr. Trump and his policies. Tester was one of the most vocal critics of Ronny Jackson, Mr. Trump's nominee to be Veterans Affairs secretary.

Alabama primary results

The AP projected Republican Kay Ivey as the nominee for governor in the GOP primary. Ivey currently serves as the state's governor, after taking over when former Gov. Robert Bentley resigned in 2017.

Mississippi primary results

The Associated Press has called the Republican primary race for Senate in favor of incumbent Sen. Roger Wicker.

Mr. Trump tweeted Tuesday morning ahead of the election, urging his support of Wicker who has "done everything necessary to make America great again!"

"Get out and vote for Roger, he has my total support!" he added.

The special election to replace retiring Republican Senator Thad Cochran will not take place until November 6. Since Mississippi special elections are nonpartisan, all candidates will run together on a single ballot in November, regardless of political party.

If no one receives more than 50 percent of the vote, the top two vote-getters will advance to a runoff three weeks later.

The AP called the Republican race in Mississippi's 4th Congressional District for incumbent Rep. Steven Palazzo. He defeated primary challenger Brian Rose.

New Jersey primary results

The Associated Press has called the Democratic Senate primary for incumbent Sen. Bob Menendez, although the race was a close one for an incumbent against a little-known candidate. Menendez decided to run for Senate again after the Justice Department decided not to re-try a corruption case against him.

The AP also called the Republican primary for U.S. Senate in favor of wealthy former biopharmaceutical executive and Marine Bob Hugin. Hugin defeated construction company executive Brian Goldberg, according to the AP. Hugin is a former Celgene Corp . executive.

The AP also called the Democratic primary in the state's 11th District for former Navy pilot and former federal prosecutor Mikie Sherrill. Sherrill won a five-way race in the district Democrats hope to flip with the retirement of Republican Rep. Rodney Frelinghuysen.

In the 11th Congressional District, Republican New Jersey Assembly Jay Webber won the party primary, according to the AP.

In New Jersey's 2nd congressional district, which includes Atlantic City and CBS News rates as very likely competitive in November, the DCCC's endorsement of Jeff Van Drew to fill retiring Republican Rep. Frank LoBiondo's seat left many progressives frustrated.

Congress – Balance of power at stake

Democrats will need to flip 23 seats in Republican-held districts in order to gain control of the House in 2018. CBS News rates 13 of the congressional districts holding primary elections on Tuesday as "very likely" or "probably" competitive this fall. Meanwhile, senators in California, Mississippi, Montana and New Jersey all face primary challenges.

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