The heat is officially on for Gov. Scott Walker.

After Tuesday's primary, the Wisconsin Republican now faces one of the most high-profile Democratic opponents of his career, as well as his third election in just four years.

Democrat Mary Burke waltzed into her party’s nomination last night, taking 83 percent of the vote. So the Wisconsin governor’s race, which the progressive Cap Times described as “the three biggest months of Scott Walker’s political career,” has now started in earnest.

Expect fireworks. Just last week, Walker sent out a desperate-sounding fundraising email suggesting this contest will be rougher than his dramatic 2012 recall election.

“I thought the Union-led recall campaign against me would be my toughest race,” the email said. “I was wrong. A new independent poll shows I'm in a TIE with my Democratic opponent for re-election. And it's because national unions and a dozen liberal Super PACs are planning to outspend conservatives.”

Stakes are unusually high for both Democrats and Republicans in this contest.

For Walker, his 2016 presidential ambitions are on the line. And for Democrats, the contest is a chance to take power in a key swing state and get another female governor.

Though they’ve had much greater success than Republicans in sending women to the Senate and House of Representatives, Democrats only have one female governor ( New Hampshire’s Maggie Hassan) while Republicans have four.