While House candidates in crowded primaries across the South have struggled to raise funds this cycle, one GOP primary in Alabama is uniquely flush with cash.

Three Republicans running for the open 6th District seat announced raising more than $300,000 each in the final fundraising quarter of 2013. A fourth candidate wasn’t far behind with $250,000.

It’s rare for so many candidates in one race to raise such sizable sums, especially in the fourth quarter, when donors’ time and resources are drained from the holiday season. The numbers are even more surprising for a House race in the South, where funds have been hard to come by in some cases this cycle.

But Republican operatives noted that the race is likely to see even more money flow in from the district’s wealthy Birmingham residents, who have a history of spending heavily for political candidates.

“There’s a mentality here of big-money giving, especial when it comes to politics,” said one Republican operative involved in the race. “The business class is accustomed to giving money.”

State Rep. Paul DeMarco raked in $367,000 in the fourth quarter, businessman Will Brooke raised $320,000, surgeon Chad Mathis brought in $350,000, including personal funds, and social conservative and activist Gary Palmer raised $250,000.

The four Republicans are looking to succeed Rep. Spencer Bachus, the former chairman of the Financial Services Committee. He announced his retirement at the end of September, giving each a full quarter to ramp up their campaigns and raise money.

With just more than four months to go until the primary, the solid fundraising across the board makes pinpointing a front-runner in the field more difficult. The winner will be strongly favored in the general election in this heavily Republican district.

“It’s hard to raise money in primaries, and those are all big numbers,” Alabama Republican strategist David Mowery said. “It’ll be interesting to see who can sustain it and where their support is coming from.”

Earlier this year, nine Republican candidates running in a special election in Alabama’s 1st District raised less than $1 million combined for the race. In neighboring Georgia, the dozen or so candidates running in three open House seats have struggled to break the $100,000 mark in each of their quarterly hauls.

GOP operatives in the Yellowhammer State said that beyond the 6th District’s financial advantages, the strong fundraising there can also be attributed to the quality of the candidates in the race.

Republican strategists said Brooke, a former chairman of the Business Council of America, has been raising money for political causes for decades and has a network of wealthy members of the state’s business community that can help boost his candidacy.

DeMarco has the advantage of a geographic base in his state House district, where he has proved to be an adept fundraiser, Alabama Republicans said. Palmer has ties to the social conservative base in Alabama, having launched the Alabama Policy Institute, a think tank with headquarters in the district.

Republicans say the real wildcard in the race is Mathis, a doctor who has positioned himself as the tea party candidate. The question, Republican strategists say, is whether Mathis can appeal to the kind of Republican located in this Birmingham-based district.

“This district is PTA, country club Republicans — not we-need-to-defund-Obamacare Republicans,” one unaffiliated Republican said. “That’s the No. 1 question in that district: Does a tea-party-type candidate play in that district?”

While the candidates released their quarterly numbers before the Jan. 31 deadline, not all have filed their official reports with the Federal Election Commission. Without seeing the reports, it’s unclear where each candidates’ funds came from, how much was from donors within the district and how much they had left in their respective war chests at the end of the year.

The 6th District primary takes place June 3. If no candidate receives more than a majority of the vote, a runoff will take place July 15.

An earlier version of this article misstated the threshold needed to avoid a runoff in Alabama. More than a majority of the vote is needed.