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.
Polls in Alabama, Mississippi, New Jersey and South Dakota closed first, at 8 p.m. Eastern. California polls don't close until 11 p.m. Eastern, so get ready for a long night.
Follow primary election live updates below:
Alabama primary
Polls have closed in Alabama
In addition to a primary election for midterms, Alabama will be holding a gubernatorial election on Tuesday. The ballot in Alabama includes incumbent Republican Governor Kay Ivey who is running for a full term in office after filling the vacancy left by the resignation of former Gov. Robert Bentley in 2017. Polls closed 8 p.m. ET.
California primary election
Polls are open in California from 10 a.m. to 11 p.m. ET
California will hold races for the House, Senate and gubernatorial primaries on Tuesday in what is 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. That means it's possible that one party has no options on the ballot come 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.
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. Incumbent Sen. Dianne Feinstein, a Democrat, faces challenge from the state Senate leader Kevin de León. 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 Devin Nunes.
Get the vote out in California today for Rep. Kevin McCarthy and all of the great GOP candidates for Congress. Keep our country out of the hands of High Tax, High Crime Nancy Pelosi.
Meanwhile, Mr. Trump has endorsed candidate John Cox over GOP challenger state Assemblyman Travis Allen. The choice could splinter the Republican vote, which might lead to two Democrats on this November's ballot.
In High Tax, High Crime California, be sure to get out and vote for Republican John Cox for Governor. He will make a BIG difference!
In addition to a primary for the state's House election, Iowa Democrats will decide a candidate for governor of Iowa. The winner will face off against Republican Governor Kim Reynolds this fall.
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.
Mississippi
Polls have closed in Mississippi
In Mississippi, incumbent Republican Sen. Roger Wicker is running for re-election. Mr. Trump tweeted Tuesday morning ahead of the election, urging his support of Wicker who has "done everything necessary to make America great again!"
Senator @RogerWicker of Mississippi has done everything necessary to Make America Great Again! Get out and vote for Roger, he has my total support!
"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.
Montana voting today
Polls are open in Montana from 9 a.m. to 10 p.m. ET
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.
New Jersey
Polls have closed in New Jersey
In New Jersey, incumbent Democratic Sen. Bob Menendez is expected to win the nomination and will likely face off against Republican challenger Bob Hugin in November. Hugin is a former Celgene Corp. executive. In New Jersey's 2nd 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.
New Mexico
Polls have closed in New Mexico
In New Mexico, Democrat Michelle Lujan Grisham is hoping to receive the nomination for governor. If she wins in the fall, she would take over from another Hispanic female governor, Susana Martinez, who is term limited. The polls closed at 8 p.m. ET.
South Dakota
Polls have closed in South Dakota
In South Dakota, Rep. Kristi Noem is vying against state Attorney General Marty Jackley to be the GOP gubernatorial nominee in that heavily Republican state.
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.
