Dick Cheney has said he believes his support of gay marriage could have sunk President George W. Bush's prospects for office in 2000.

In his first interview since receiving a heart transplant in March, Cheney spoke to ABC News' Jonathan Karl, portions of which will be broadcast on This Week, Good Morning America and Nightline and World News with Diane Sawyer.

In the interview, which was conducted in Jackson Hole, Wyoming, Cheney said he did not see any reason for raising the issue of gay marriage in 2000.

“Why?” he answered when Karl asked whether he should have expressed his support for the institution.

In June, Mary Cheney married her longtime partner Heather Poe in Washington, D.C.

“I'm sure it was fine,” Cheney, 71, said of his daughter's wedding ceremony. “We wished them well. She wanted to avoid having it be a media circus or having it become part of the political debate. So Lynne and I were very proud and happy and congratulated them.”

(Related: Dick, Lynne Cheney reiterate gay marriage support on The View.)