Political watchers are focused on Mississippi Tuesday as a heated Republican senate runoff marks a critical showdown between the tea party movement and the GOP establishment.

Coming two weeks after House Majority Leader Eric Cantor’s shocking primary defeat by an unknown tea partier in Virginia, the hard-fought race between incumbent Thad Cochran and upstart State Senator Chris McDaniel could shift the GOP narrative and affect the rest of the 2014 electoral season.

Cochran, Mississippi's six-term senior senator, was unexpectedly defeated by the tea party-affiliated McDaniel in Mississippi's Republican primary on June 3, similar to how Cantor was beaten by tea party-aligned college economics teacher David Brat in Virginia's GOP primary on June 10. Given the parallels between the two elections, Mississippi's primary runoff gained national interest almost immediately after Cantor's defeat.

On Monday, it drew Arizona senator and 2008 GOP presidential nominee John McCain to Jackson, Mississippi's capital, to campaign for Cochran.

"I call on my fellow veterans, I call on my fellow service members to send Thad Cochran, a good and decent and honorable senator, back to the United States Senate," McCain told a crowd of about 200, according to the Associated Press.

A blow to the GOP establishment
Cochran's loss sent shockwaves through the GOP establishment. Known for getting federal dollars to flow to Mississippi, Cochran entered the Senate in 1978 and has held a seat on the powerful Senate Appropriations Committee for 33 years, according to the New York Times. As a committee member, Cochran brought millions of federal dollars to the state for projects like new university campuses, highways and wastewater systems, plus billions in federal assistance to Hurricane Katrina-ravaged Gulf states in 2005.

But despite Cochran’s experience, plum committee membership, the backing of his party's establishment and his skill at bringing home legislative bacon, he lost to McDaniel, an eight-term state senator and conservative former radio host, by less than 1,400 votes, forcing the runoff.

As a result, the contest has been described in terms like "a referendum on government spending" and "a battle for the heart and soul of the Republican Party."

Tea party supporters are hoping that Cochran will be the next GOP bigwig to lose to an underdog tea party candidate.
And political observers, many of whom until earlier this month were writing the movement's obituary, are looking to see if the tea party is a viable, re-energized force that's able to fight for the future, direction, and philosophical core of the Republican Party -- or not. 
On Monday, McDaniel concluded his campaign by telling supporters that their disgust for Washington will make them win, the AP reported. The tea party favorite described Cochran as "liberal." 
"Tonight, they're calling us unstoppable," he told his supporters. "It's contingent on you getting out to the polls, bringing your friends with you. If you do that, with that kind of turnout, there's nothing the Washington elite can do."