On Tuesday, voters in four states will participate in their state's primary or caucuses. Hawaii and Idaho only hold Republican caucuses while Michigan and Mississippi are holding primaries for both parties.
Hillary Clinton or Bernie Sanders are the two candidates in the Democratic race while four contenders remain in the Republican race: Donald Trump, Marco Rubio, Ted Cruz and John Kasich. Ben Carson officially dropped out of the race on Friday.
- Watch CBSN for coverage of Super Tuesday at 6 p.m. ET
The polls in Michigan and Mississippi are open until 9 p.m. and 8 p.m. ET, respectively, while polls close in Idaho at 11 p.m. ET and Hawaii caucus sites will close around 1 a.m. ET on Wednesday. For Democrats, about 188 delegates are up for grabs and 150 delegates are at stake for Republicans.
These four contests come two days after Rubio won Puerto Rico and Sanders won Maine. They also take place three days after Sanders won Nebraska and Kansas; Clinton won Louisiana; Trump won Kentucky and Louisiana; and Cruz won Kansas and Maine.
A week from now, some of the state contests will become winner-take-all, which could help the frontrunners expand their delegate counts and help winnow down the rest of the fields.
According to CBS News' latest count, Trump has 378 delegates while Cruz has 298 delegates. Rubio is trailing them with 146 delegates and Kasich only has 35. For the Republicans, a candidate needs 1,237 delegates in order to clinch the nomination. On the Democratic side, Clinton has picked up 1,123 delegates while Sanders has accumulated 484 delegates. A candidate needs 2,383 delegates in order to win the nomination.
A CBS News battleground tracker poll released Sunday found 39 percent of GOP primary voters in Michigan back Trump while 24 percent support Cruz, 16 percent back Rubio and 15 percent back Kasich. On the Democratic side, 55 percent said they support Clinton while 44 percent support Sanders. Two Monmouth University polls released Monday also found Trump leading in Michigan and Florida and Clinton leading Sanders in Michigan.
The two Democratic candidates faced off at their seventh debate in Flint, Michigan on Sunday night where they argued about the 2008-2009 auto bailout to save the auto industry and discussed how to solve issues like the Flint water crisis.
Trump has been leading the GOP field, but Cruz is catching up and Republicans are now speculating about the increasing chances of a brokered or contested Republican National Convention in July.
Trump reiterated to CBS' "Face the Nation" on Sunday that he is "very much a unifier."
"I mean, I get along with people. I'm a unifier. I'm very much a unifier," Trump said. "And maybe people don't see that. But they will see that."
In the GOP race, former California Gov. Arnold Schwarzenegger endorsed John Kasich on Sunday.