Dr. Greg Brannon, the Tea Party-endorsed candidate in North Carolina’s May 6 Republican Senate primary, is emerging as the top challenger to GOP Establishment-backed front runner, Thom Tillis.

Tillis, Speaker of the House in the North Carolina House of Representatives, was expected to sail to the nomination. But two and a half weeks before the primary, Brannon appears to have strong momentum.

Brannon has the endorsements of Tea Party favorites Senator Rand Paul (R-KY) and Senator Mike Lee (R-UT), as well as many of the leading national Tea Party groups, including FreedomWorks and the Tea Party Patriots Citizens Fund.

A PPP poll conducted between April 3 and 6 shows a tight race, with a plurality of North Carolina’s Republican primary voters still undecided. In a five person race, Tillis leads with only 18 percent, followed by Brannon at 15 percent.

43 percent of Republican primary voters in the PPP poll were undecided, an unusually high number so close to an election. This suggests the outcome hangs in the balance, and turns on which candidate can best communicate their views to persuade these undecideds over the next few weeks.

If no Republican receives more than 40 percent of the vote on May 6, the top two candidates will meet in a July runoff primary election.

The announcement on Thursday by conservative columnist Ann Coulter that she has endorsed Brannon added to the Brannon campaign’s momentum.

Coulter pulled no punches, calling Brannon’s opponent Tillis a “foreign-labor cheerleader.”

According to Coulter, “Tillis championed a bill making it easier for North Carolina employers to hire foreign workers. Instead of temporary guest workers coming in for a few months a year to do farm work, Tillis’ bill expanded ‘farm labor’ to ‘all industries,’ and expanded ‘seasonal’ to ‘nine months.’ “

Coulter urged North Carolinians to “repay [Tillis] for driving down their wages on May 6.”

Brannon, an obstetrician-gynecologist, has had a private practice in North Carolina for twenty years. According to his campaign web site,  he has a “patient network of more than 20,000.”

His campaign biography describes him as “one of North Carolina’s leading voices on health care,” who has “experienced firsthand a healthcare system in disarray.”

Incumbent Democratic Senator Kay Hagan (D-NC), who squeaked to victory in 2008, is considered highly vulnerable. Most analysts project North Carolina as a possible Republican pickup in the November general election. 

For that reason, the outcome of next month’s Republican U.S. Senate primary in the Tar Heel State is significant at a national level for both Democrats and Republicans. Fred Barnes of the Weekly Standard called a Republican victory in North Carolina’s Senate race “key” to the possible Republican takeover of the Senate.

Voters in North Carolina have been subjected to a heavy barrage of television ads over the past few weeks coming from independent groups. Karl Rove’s American Crossroads has spent $1.1 million on television ads attacking Hagan and supporting Tillis. Americans for Prosperty has spent heavily attacking incumbent Democrat Hagan. Brannon, who has raised less money than Tillis for the Republican primary, has focused mainly on direct mail and online advertisements.

Federal Election Commission records show that the Tillis campaign had $1.2 million in cash on December 31, 2013. The Wall Street Journal reports he raised $1.3 million in the first quarter of 2014. But he spent more than he raised. According to the Journal, the Tillis campaign had $1 million in cash on March 31, the ending period for first quarter reports that were due to be filed on April 15 with the FEC. The FEC website does not yet report first quarter results for the Tillis campaign.

In contrast, FEC records show the Brannon campaign had only $143,000 in cash on December 31, 2013. The FEC website does not yet report first quarter results for the Brannon campaign.