President Donald Trump attacked fiscal conservative Rand Paul as "crazy" on Tuesday morning as he urged reluctant Republican senators to move quickly on his massive tax and spending package.

The Kentucky senator had previously said on CNBC that he would not vote for the bill signed by the president because it would raise the legal U.S. debt limit.

"I disagree with that. It's not conservative," said Paul, who has also argued that the tax measure would add too much to the national debt.

Trump quickly responded with a series of social media posts, saying the senator "never has a practical or constructive idea. His idea is actually crazy (loser!)"

But Senate Republican Leader John Thune of South Dakota said the debt ceiling must be raised and "failure is not an option." The Treasury Department estimates the U.S. will run out of borrowing authority in August or September.

Thune acknowledged that it would take time to resolve the conflicting demands of the 53 Senate Republicans and craft a package acceptable to a majority of the 100-member body. All Democrats are expected to oppose the measure. "We have to get to 51, so we'll figure out a way forward to do that over the next few weeks," Thune told reporters. Read more: Senate Begins Signing Off on Trump's Tax and Debt Limits Bill While most outside economists have predicted the House version of the bill would add trillions of dollars to the U.S. debt over 10 years, the White House has claimed the tax bill would pay for itself in part through economic growth.

Trump and Republican leaders have said they had no choice but to add the debt ceiling to the tax bill to ensure smooth passage and avoid a default as early as August. Paul posted a response to Trump, saying he supports tax cuts but "I would also like to see $5 trillion of new debt removed from the bill," adding that at least three other Republican senators agreed with him, enough to block the bill.

But other conservative opponents of the bill have not said they would oppose any increase in the debt ceiling in the bill. Florida Sen. Rick Scott has said he wants to balance the budget to avoid future increases, but noted that he voted for the budget outline that allows for a ceiling increase. Wisconsin's Ron Johnson has said he could support a smaller one-year debt ceiling increase in exchange for big spending cuts. (alg)

Source: Bloomberg