Sen. Tom Harkin (D-Iowa) on Friday ramped up Democratic pressure on the White House to consider invoking the 14th Amendment to raise the debt ceiling.

"Is there anything that prohibits him from doing that? The answer is no," Harkin said, adding that the White House has been going about the idea the wrong way by asking whether the amendment legally gives the president the power to raise the debt ceiling without congressional authority.

Although President Obama indicated last week that his lawyers had looked into the legality of the so-called “14th Amendment solution,” he said they were “not persuaded that that is a winning argument.”

White House press secretary Jay Carney made clear in a briefing on Tuesday that the option was not on the table. “The Constitution makes clear that Congress has the authority — not the president — to borrow money,” Carney said. “And only Congress can increase the statutory debt ceiling. That’s just a reality.”

But Harkin called it “nuts” for the White House to indicate it would not consider the option. “It should be on the table," he said on the liberal Bill Press’s radio show.

Harkin is not the only one pushing for the president to step in as negotiations over the debt ceiling remain deadlocked between Republicans and Democrats in Congress and the Treasury Department’s Aug. 2 deadline nears.

Sens. Bernie Sanders (I-Vt.) and Charles Schumer (D-N.Y.) have likewise indicated that the president should look into the legality of invoking the 14th Amendment.

Most of the pressure is coming from the House side, with Minority Whip Steny Hoyer (D-Md.), Assistant Democratic Leader James Clyburn (S.C.) and Rep. Chris Van Hollen (D-Md.) discussing the amendment as a possible solution.

Harkin said he has spoken to White House officials about the possibility. “I think [Obama] knows my feelings on that.

"I think this is one time where it's very clear the president can invoke the 14th Amendment,” he said, arguing that it would not be without precedent.

Harkin compared the idea to former President Lincoln making the Emancipation Proclamation, an example Clyburn used as well, or former President Franklin Roosevelt’s Lend-Lease program, which allowed the U.S. to support Allied nations before declaring war in 1941.

Republicans have warned they would take the president to court if he tried invoking the amendment over the debt ceiling. "I think he wins" in a court challenge, Harkin said.

"I think the American people would stand up and applaud a president who had the guts and the courage to stand up and make sure the political battles don't tear this country apart,” he said. “I think the Tea Party will probably go nuts, but what the heck, they're already nuts anyway.”

Harkin added that the majority of moderates on both the Republican and Democrat side would probably “silently applaud” Obama for the decision, as well. “They don't want to vote on raising the debt ceiling anyway.”