LAS VEGAS >> President Barack Obama is putting people on notice: He’s back from vacation feeling “refreshed, renewed, recharged” — and “a little feisty.”

He immediately showed his feisty side.

At a Democratic fundraiser Monday night in Nevada, Obama declared himself ready for the challenges he faces this fall in dealing with a Republican Congress that disagrees with him on the budget, energy policy, education and much more.

Obama said that as he’d ridden to the fundraiser with Senate Democratic leader Harry Reid, they’d done some reminiscing and spent some time “figuring out how we are going to deal with the crazies in terms of managing some problems.”

He didn’t identify exactly who the two of them had defined as “crazies.”

But Obama spoke at length about his differences with the GOP Congress. And he lamented that “too often, our political debates are not about what’s best for the country but what’s best for the next election.”

If the country is to remain a strong world leader, he said, it needs “not just a president who, after a few gray hairs, seems to know what he’s doing, but we also need a Congress that functions.”

Obama also looked beyond the immediate challenges to simpler times down the road.

He said that since neither he nor Reid is seeking re-election next year, the two off them had talked about “riding off into the sunset together.”

Earlier Monday, Obama spoke at a green energy conference where he accused fossil fuel interests and other critics of his energy policies of trying to restrict consumers from accessing solar, wind and other renewable sources in order to protect the status quo.

“That’s not the American way,” Obama said. “This is about the past versus the future. America believes in the future.”

The president also questioned the ideological consistency of those who champion free-market solutions — except when the free market is pointing to the wisdom of renewable energy. He singled out billionaire brothers Charles and David Koch, who are major donors to Republican political candidates.

“It’s one thing if you’re consistent in being free market,” Obama said. “It’s another thing when you’re free market until it’s solar that’s working and people want to buy, and suddenly you’re not for it anymore. That’s a problem.”

In a statement, Koch Industries’ Philip Ellender said the company “supports all forms of energy, but we believe they need to stand on their own merits. Koch has consistently lobbied for the repeal of taxpayer-funded subsidies and mandates. Even though they may benefit us in the short-term, we will continue to fight these market-distorting policies and special deals, and we will continue to call them what they are — corporate welfare.”

Obama said the economics are now such that “solar isn’t just for the green crowd any more, it’s” for the green-eyeshade crowd too.”

Fossil fuel and utility interests have been working at the state level and elsewhere to undercut clean energy policies with arguments that the matter should be left to the free market.