Sen. Ted Cruz (R-Tex.) said Monday that it would be "irresponsible" for House Republican leaders to allow for a debt ceiling increase without "significant" progress toward reducing spending.

House GOP leaders are currently weighing what -- if anything -- to ask for in exchange for a debt ceiling hike. But many believe they'll wind up passing a "clean" hike -- with no additional elements.

"I think that's irresponsible," Cruz said after a speech at the Heritage Foundation. "I hope the House doesn't go down that road."

Cruz said Republicans and Democrats should come together to reduce the debt. He declined to prejudge whatever proposal comes from House GOP leaders but said its should be more than just a token concession.

"We'll have to wait to see what the details are, but in my view we should not raise the debt ceiling without significant structural reforms to fix the problems and stop the out of control spending," Cruz said.

Cruz’s comments Monday echo what he was telling reporters last week – that his GOP colleagues in the House should continue fighting to raise the borrowing limit with strings attached. “History makes clear that the debt limit is the only effective, or one of the few effective, lever points for meaningful spending restraint,” he said last week.

Earlier, in his speech to Heritage's Conservative Policy Summit, Cruz said that environmentalists should line up behind the Keystone XL pipeline because it's a safer and better way to transport oil.

“If you are a Birkenstock-wearing, tree-hugging Greenpeace activist, you should love the Keystone pipeline," Cruz said. He added that, if the pipeline isn't built, energy companies will find a less environmentally friendly way to move their product.

Cruz was talking about his American Renaissance Energy Act -- a series of steps to expand American energy production and exploration. As we wrote this morning, Cruz is pushing for a conservative energy approach focused on more than just the Keystone pipeline, which the Obama administration is still deciding whether to move forward with.

Cruz, a potential 2016 presidential candidate, noted that Obama's former energy secretary, Steven Chu, recently said that the decision on whether to build the pipeline is a political one more than a scientific one.

"The only thing that can stop this energy renaissance is the government getting in the way," Cruz said.