On Tuesday, voters in eight states — Mississippi, Alabama, California, Iowa, Montana, New Jersey, New Mexico and South Dakota — nominate House, senate and gubernatorial candidates for the Nov. 4 elections.
And the three matches to watch closely will take place in Mississippi, where an incumbent Republican senator is facing off against a Tea Party challenger, along with Iowa and Montana, where Republicans hope to seize Senate seats from Democrats.
Considering that control of the Senate likely remains up for grabs and the fierce nature of the Republican race in Mississippi between the Tea Party and the GOP "establishment," those three primaries could give a glimpse of things to come.
Six-term incumbent Republican Sen. Thad Cochran and Tea Party-backed challenger Chris McDaniel are locked in a dead heat after a messy race, according to the Real Clear Politics average of recent polls. Whoever wins Tuesday would be the favorite to win in November, since Mississippi is one of the most heavily Republican states.
Ernst, who made headlines in March with an ad boasting of her ability to castrate hogs, has built up a commanding lead in recent polls. The RCP average puts her at 33.7 percent, to 18.3 percent for Jacobs -- but she still needs to reach 35 percent in Tuesday's vote to avoid kicking the decision to delegates at a June 14 convention.
It looks increasingly likely that Rep. Steve Daines, who has the support of the National Republican Senatorial Committee, will breeze past his primary challengers, Montana state Rep. Champ Edmunds and Susan Cundiff, to face off in November against incumbent Democrat John Walsh.
Walsh, who was appointed in February to replace Democratic Sen. Max Baucus, is also expected to coast to victory against his primary challengers, including rancher Dirk Adams and former Lt. Gov. John Bohlinger.
Daines is a heavy favorite against Walsh, according to the RCP polling average.
Therefore, according to CNN, analysts say Walsh's success in November could be determined by how easily he defeats his primary challengers Tuesday.