Bernie Sanders pulled off a shocking upset in Michigan's Democratic primary Tuesday night, beating Hillary Clinton in a race that most polls had him trailing by double digits and eclipsing the front runner's earlier win in Mississippi.

Republican front-runner Donald Trump, meanwhile, regained any momentum lost last weekend against challenger Ted Cruz, sweeping to convincing victories in Michigan and Mississippi while sending a message to the Republican establishment to jump on board — or get out of the way.

Cruz was projected to pick up a win in the Idaho GOP primary, while Trump was projected to easily win the Hawaii Republican caucus.

But Trump's earlier victories were more valuable in terms of delegates. And Tuesday's results may also seal the fate of Marco Rubio, who appeared once again to finish the night failing to gain any delegates.

Cruz appeared to have beaten John Kasich for second place in Michigan by approximately 8,000 votes. Kasich is counting on a win in his home state of Ohio next week to salvage his campaign.

On the Democratic side, Clinton easily won Mississippi’s primary earlier Tuesday, thanks in part to her overwhelming support from black voters, and likely will pick up more delegates in Tuesday’s contests than Sanders.

But the Vermont senator’s surprising Michigan win could give him a bounce as he and the rest of the candidates charge into the vital March 15 primaries in Florida, Ohio, Illinois, Missouri and North Carolina.

Michigan is the ninth and largest state that Sanders has won so far in the Democratic presidential campaign. All 15 pre-election polls in Michigan this year showed Clinton leading Sanders by double digits.

For his part, Trump is looking to March 15 to sideline the rest of the GOP field for good – something he tried to start doing Tuesday night. At a press conference at his golf club in Juniper, Fla., he said of his remaining rivals, “They’re pretty much all gone.”

Michigan was the biggest prize of the four states that voted Tuesday.

On the Republican side in Mississippi, Trump defeated Cruz by 47 percent to 36 percent of the vote, with Kasich a distant third at 9 percent and Rubio garnering just 5 percent of the vote.

Trump celebrated his wins at a lengthy press conference Tuesday night, teasing the “special interests” and others that ran ads against him.

“It shows you how brilliant the public is, because they knew they were lies,” Trump said.

He started his victory talk with a subdued and conciliatory tone, appearing to take the first steps to patch up any differences with the party brass. He noted House Speaker Paul Ryan recently called him.

“He could not have been nicer,” Trump said.

But he soon slipped into his standard fare, making cracks about his remaining rivals. He took a shot at Cruz, noting the Texas senator positions himself as the only candidate who can beat him, “but he never beats me.”

Both Trump and Clinton had a mixed performance this past weekend where they effectively split the delegate field with their top rivals.

The stakes on Tuesday arguably were higher for Trump, whose delegate lead over Cruz shrunk on Saturday as they each won two contests. Cruz has been pushing to consolidate conservative support on the heels of those races, arguing Trump is not the candidate he claims to be.

“He is pretending to be an outsider,” Cruz told Fox News.

But Trump used his wins Tuesday to downplay the chances for his remaining rivals, as he and the rest of the field look ahead to next week’s vital winner-take-all contests in Ohio and Florida.

“I think we’re going to do really well in Florida,” he said. “It’s my second home.”

Kasich, who campaigned in Michigan Tuesday, told Fox News he was focusing on the Midwestern states – and repeated his vow to win Ohio.

Rubio, too, is looking for a comeback win in his home state next week, all the while battling calls from his rivals to drop out. But Trump leads in the Florida polls, and Rubio endured another disappointing night in Tuesday's contests.

Looking ahead, Rubio rallied a home-state crowd Tuesday evening, saying: “I believe with all my heart that the winner of the Florida primary next Tuesday will be the nominee of the Republican Party. ... And I need your help. I need your vote.”

Clinton, meanwhile, is still trying to regain her footing as Sanders has demonstrated his grassroots support in several recent contests. Over the weekend, he claimed three victories to Clinton’s one.

Thanks in part, though, to so-called “superdelegates” – party leaders and officials free to support whomever they want – Clinton maintains a huge delegate lead over Sanders. She had 1,221 to Sanders’ 571, as of early Wednesday morning.

Clinton communications director Jennifer Palmieri stressed Tuesday that their campaign’s strategy focuses on winning delegates, and told Fox News they’ll pick up more delegates than Sanders from Tuesday’s contests regardless of the Michigan results.

On the GOP side, Trump leads Cruz in the delegate count 446 to 347, with Rubio trailing at 151 and Kasich at 54, as of early Wednesday morning.