Despite a vicious war of words between Southampton Town Supervisor Linda Kabot and Southampton Town Republican Party Chairman Marcus Stinchi that left the incumbent supervisor ostracized by party leaders, the two struck a deal on Monday, saying it was for the good of the party.

Ms. Kabot scored a coup, capturing the Republican Party nomination for reelection without having to wage a promised primary battle. She also added the Conservative Party nomination after the GOP nominee for supervisor, Southampton Town Conservative Party Chairman Jim Malone dropped his bid for supervisor.

It was a move intended to unite the parties and strengthen the GOP’s chances of holding on to a Town Board majority this fall, Ms. Kabot said.

Instead of running for supervisor, Mr. Malone will run with Republican incumbent Chris Nuzzi for the two Town Board seats up for grabs in November. Previous Republican nominee William Wright dropped his bid for the Town Board seat, making room on the ballot for Mr. Malone.

Mr. Wright said he found out about the changes to the slate late Monday afternoon—the last day for candidates to accept or decline a nomination. “I was asked to step down for the good of the party. And I did,” he said Tuesday.

Now, Ms. Kabot will be the Republican candidate in November facing Democratic challenger Anna Throne-Holst, and Mr. Malone and Mr. Nuzzi will face incumbent Town Councilwoman Sally Pope and challenger Bridget Fleming, the Democratic nominees.

Ms. Kabot said Mr. Stinchi contacted her at around 3 p.m. on Monday to inform her that, despite the Republican Committee’s resounding rejection of her at its convention in May—the vote was more than two-to-one in Mr. Malone’s favor—the nomination for supervisor was now hers.

Suffolk County Conservative Party Chairman Ed Walsh said Tuesday that Ms. Kabot would also be the Conservative Party candidate in November.

Ms. Kabot said Mr. Stinchi, who had been critical of Ms. Kabot’s leadership in the run-up to the party’s convention, agreed to give her the nomination on the condition that she drop challenges she and several others were waging for Republican committee seats held by Mr. Stinchi, Mr. Stinchi’s mother, Pat Stinchi, and former Town Supervisor Patrick Heaney. Were she successful in that effort at the party’s reorganization meeting in September, those party members would have lost their committee status.

Ms. Kabot said she agreed to back off on those challenges in return for the party’s nod.

“I’m very happy that the political leaders have come realize that we have a greater chance of success by joining forces and coming together,” she said in a statement issued Tuesday.

Mr. Malone did not return repeated calls seeking comment on the latest developments, which came on Monday, the last day for candidates to accept or reject nominations. Mr. Stinchi stated in a e-mail that he had no comments other than what had been expressed in the party’s press release.

The move toward unity comes after a bitter war of words between Ms. Kabot and GOP leaders, in particular Mr. Stinchi—exchanges that spoke to a dysfunctional party.

Before the party’s convention in May, Mr. Stinchi refused to endorse the sitting supervisor and said her nomination was not a foregone conclusion. In turn, Ms. Kabot alleged that GOP leaders had pressured her to stop going public with the town’s financial troubles, threatening to withhold the nomination unless she complied.

Ms. Kabot went so far as to charge Mr. Stinchi with preferring a “reign of terror” style of running the committee and a “dictatorial style” of governance for the town. Ms. Kabot claimed then that revealing the town’s fiscal woes only hurt the GOP and validated her reasons for challenging Mr. Heaney in 2007

In response, Mr. Stinchi said those accusations were not only “inaccurate but insulting” and later argued that Ms. Kabot’s rhetoric likely cost her the committee’s vote.

Ms. Kabot credits Mr. Stinchi’s change of heart to Mr. Walsh, who Ms. Kabot said saw beyond the GOP infighting to the general election. “He saw past the egos and personalities and realized that the best chances of being successful in November was to present the strongest, most unified ticket,” she said.

While the Republican Party will now be entering the election season as a united front, Ms. Kabot said she’d still like to see a change in the party’s leadership—including Mr. Stinchi.

“Some of the leaders in the committee are out of touch with the rank-and-file voters,” Ms. Kabot said. “They now see that I’m a force to be reckoned with.”

Mr. Walsh said Tuesday that the shift back to Ms. Kabot reflected the desire of both the Republican and Conservative parties to avoid a bloody primary battle that would only strengthen the Democrats’ hand in November. Ms. Kabot had filed the necessary petitions last week to force a primary for the GOP nomination.