Former Republican congressman Tom Tancredo. Image credit: Ed Andrieski/AP Photo

Tom Tancredo has just said "no."

Under pressure from his wife and grandchildren, the former GOP congressman will renege on a public pledge to smoke marijuana, which he made after losing a bet on Colorado's pot-legalization initiative on Election Day.

Tancredo, a conservative Republican who has been out of Congress since 2009, supported Colorado's Amendment 64, which legalized marijuana in his home state when it passed on election day. Tancredo said he had never smoked marijuana and that he did not condone its use, but argued that the government shouldn't tell adults what they can or can't ingest.

The former congressman never thought it would pass. "I thought it would take at least one more time around to do it," Tancredo told ABC News last week. He made a bet with film producer Adam Hartle, who was in Colorado to make a film on the pot measure, agreeing to smoke marijuana if it became legal.

Recently, Tancredo said he would make good on the bet, agreeing to inhale "just a puff" with Hartle, leaving the filmmaker to handle the marijuana procurement. On Friday, he even suggested Democratic Colorado Gov. John Hickenlooper should join in.

But that made a lot of people unhappy, including Tancredo's family, and now the former congressman says he won't do it.

"My wife is absolutely-she's pissed," Tancredo told ABC News last week. "Oh man, she is not happy."

Neither were his conservative backers.

"My conservative friends just believe what I'm doing is encouraging people to smoke it," Tancredo said. "I don't think people should. That decision is up to an individual. An adult, in this society, is not something the government should have any control over."

Finally, on Friday night, Tancredo cracked under pressure from his grandchildren.

They were "very upset with grandpa," Tancredo told ABC News, and for him, that was it.

"Will have to welch. Political heat is one thing. Am use to that," Tancredo wrote in an email. "Heat from my family is quite another."