"Absolutely, they're not realistic," the retiring House speaker said of hard-line conservatives and outside groups in a Sunday interview on CBS' "Face the Nation."
He pointed to the October 2013 shutdown after conservative House Republicans demanded the repeal of President Barack Obama's signature health care law as one maneuver -- led by Texas Sen. Ted Cruz -- that was never going to succeed.
"The Bible says beware of false prophets. And there are people out there, you know, spreading noise about how much can get done. I mean this whole notion that we're going to shut down the government to get rid of Obamacare in 2013 -- this plan never had a chance," Boehner said.
"But over the course of the August recess in 2013 and in September, a lot of my Republican colleagues who knew this was a fool's errand -- really, they were getting all this pressure from home to do this," he said.
Boehner said conservative, Washington-based groups knew the goals they were championing couldn't be accomplished but pressed for them anyway.
"And so, we've got groups here in town, members of the House and Senate here in town, who whipped people into a frenzy believing they can accomplish things that they know -- they know -- are never going to happen," he said.
Asked specifically if Cruz, a GOP presidential candidate, was a "false prophet," Boehner didn't dispute it. He even pointed to his comment at a private fundraiser, leaked to reporters later, that Cruz is a "jackass."
"You can pick a lot of names out. I'll let you choose them," he said.
Asked about his own regrets, Boehner pointed to the collapse of the "grand bargain" -- a deal he and Obama had quietly put together that would have addressed the debt limit and government spending long-term.
"It's probably one of the biggest disappointments in my speakership," he said. "We were so close -- we had an agreement. And two days later, the President walked away from it. It would have saved about $5 trillion over 10 years, it'd have been good for the economy, it'd have been good for our country, it'd have been good for our kids and grandkids. But you know, it's Washington."
The advice Boehner said he'd offer the next speaker sounded similar to his criticism of his party's right wing. He urged his successor to accept that small victories are sometimes the best that can be done in a complicated, split system of governance.
"Keep the country's best interest in mind and have the courage to do what you can do," Boehner said. "In our system of government, it's not about Hail Mary passes. It's the Woody Hayes school of football -- three yards and a cloud of dust. Three yards and a cloud of dust. It's a slow, methodical process."