A week after President Donald Trump announced he was withdrawing from the Iran nuclear agreement, billionaire casino magnate Sheldon Adelson rewarded five Republican candidates with campaign donations. They all had one thing in common: they had adamantly opposed the Obama-era agreement.

Three of them are also among the most vulnerable GOP candidates running in the midterm congressional elections.

Nevada Republican Sen. Dean Heller, Virginia Rep. Barbara Comstock, California Rep. Mimi Walters, Utah Rep. Mia Love and Republican candidate for Congress in Nevada’s 4th District Cresent Hardy all received campaign contributions from Adelson in May, according to Federal Election Commission records.

The campaigns of Heller, Hardy and Love each received $5,400 while Comstock and Walters picked up $2,700 from Adelson, records show. Heller, Hardy and Comstock have received contributions from Adelson in the past while Love and Walters are first-time beneficiaries.

In a statement to CNBC, Heller's campaign said the senator has consistently taken a stand against the Iran deal.

“Dean Heller’s positions on Israel and the Iran Deal have been longstanding and consistent,” a campaign spokesman said. “He has said from day one that the Iran Deal was not good for America or our allies.”

A spokesman for the Walters campaign said Walters' support of Israel was a bigger attraction to Adelson than her position on Iran.

“We are happy to receive a contribution from Sheldon Adelson but it doesn’t have to do with her position on the Iran deal," the spokesman said. "She has visited Israel many times and she’s big supporter of Israel." He did add that "she’s been very clear about her position against the Iran deal."

Representatives for Adelson and the three other campaigns did not return requests for comment.