Obstetrician and 2014 Senate candidate Greg Brannon barely snuck under Monday’s filing deadline to challenge North Carolina Sen. Richard Burr in March’s primary.

Whether that’s too late for Brannon to amass the tea party support he might need to unseat a two-term senator remains to be seen, but so far, the kinds of groups that would back an anti-incumbent challenger such as Brannon don’t sound effusive about his candidacy.

“He’s solid on economic conservative issues, and certainly if there was an opportunity to meet with him we would,” Club for Growth Communications Director Doug Sachtleben said Tuesday.

But the Club didn’t get involved in last year’s primary, when eight Republicans were vying for the nomination to unseat former Democratic Sen. Kay Hagan. Brannon won 27 percent of the vote, finishing second to now-Sen. Thom Tillis.

Brannon earned the backing of Kentucky Sen. Rand Paul and Utah Sen. Mike Lee in 2014, but a National Review analysis last year showed tea party groups spending less than $200,000 on his candidacy. Only one major tea party group — FreedomWorks — backed him in the primary.

And this year, FreedomWorks’ message sounds similar to the Club’s.

“If he wants to to come in and talk to us, we’re open to that,” said FreedomWorks spokesman Jason Pye, who explained that the group has become more selective in its endorsements. “We want to see a viable path to victory as well as fundraising capabilities,” he added.

Senate Conservatives Fund, which did not play in 2014’s primary, is also watching and waiting, with the question of viability front-and-center.

“We don’t know at this time if we will get involved, but we’re going to watch the race carefully. Richard Burr’s record in the Senate has been a major disappointment for many North Carolina Republicans and we could get involved if there is real chance to replace him with a strong conservative,” SCF President Ken Cuccinelli said in a statement.

Fundraising viability is a major concern in a presidential battleground state where already expensive media markets will be even pricier.

Brannon filed a termination report with the FEC in February 2015 showing his campaign had just $13,268 in its account. Burr ended the third quarter with more than $4.7 million in the bank.

And a fraud case that surfaced during the last campaign is still pending against Brannon. His campaign could not be reached for comment.

The lukewarm reception of Brannon’s candidacy, however, doesn’t mean the appetite to oust Burr isn’t there.

“Burr needs to be Cantorized,” read one comment on a conservative blog about Brannon’s entrance into the race, referring to then House Majority Leader Eric Cantor’s stunning defeat in the 2014 GOP primary.

Burr has suffered from low favorability ratings, and although he has an 82 percent lifetime rating from the Club for Growth, his yearly score has been declining since 2010.

“It’s not a terrible score,” Sachtleben said. “But certainly one that if there was a strong viable candidate, and we saw a path to victory with [a candidate] that would be an upgrade, we’d take a look,” he added.

But with the primary 90 days away, it might be too late.

Some tea party activists in North Carolina see Brannon, who earlier this fall formed the 501(c)4 nonprofit Organizing for Liberty, as more of a libertarian than a tea party candidate. And they balked at FreedomWorks’ 2014 endorsement of Brannon.

“It’s not what the rural tea party movement wanted in North Carolina,” said Surry County Tea Party Patriots’ Kevin Shinault. “It wasn’t that we were against Greg Brannon,” he said, “we were against one outside source.”

The Burr campaign’s general counsel, Paul Shumaker, wasn’t surprised that his candidate attracted a primary challenge or that it was Brannon — “it’s reflective of the environment,” he said, adding that for decades, every incumbent Tar Heel senator from both parties has attracted a primary challenge.

But he maintained that the dynamics of a 2016 race will be different from 2014. “Whereas Tillis and Brannon were both unknown entities across the state, Brannon’s identity is much less” in a year when the presidential race should bring out more voters, he said.

The Democratic side will also have a primary, with former state Rep. Deborah Ross enjoying the most establishment support from Washington. Spring Lake Mayor Chris Rey, failed 2014 primary candidate Ernst T. Reeves (who earned 9 percent of the vote), and Durham businessman Kevin Griffin are also vying for the Democratic nomination.

Libertarian Sean Haugh, the pizza deliveryman who ran in 2014, has filed to be on the ballot again next year.

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