WASHINGTON — After the dramatic failure of Republican efforts to repeal and replace Obamacare, a frustrated President Trump has renewed his call for the Senate to throw out its filibuster rule and push through his agenda with a simple majority vote.

"Don't give up Republican senators, the World is watching: Repeal and Replace ... and go to 51 votes," Trump tweeted Sunday, repeating calls he made earlier in the weekend to kill the filibuster.

But experts say the president's unsolicited advice ignores two major realities.

First, the Senate health care bills were not filibustered by Democrats, who were prevented by Republicans from using that tool. GOP leaders employed a budget procedure to allow the bills to be approved with just 51 votes. Republicans, who hold 52 seats in the Senate, failed because they could not convince enough of their own senators to support the bills. The final bill brought to the Senate floor early Friday morning failed 49-51, with three Republicans voting against it.

Second, asking senators to give up the filibuster is asking them to give up their greatest power.

"An individual senator's ability to prolong debate and block a vote is what makes senators, even a freshman, very powerful," said Frances Lee, a political science professor at the University of Maryland. "They can force coalition-builders to come and talk to them, find out their issue and try to accommodate them ... So they wouldn't give up that power unless the Senate literally could not function. Even then, it might be hard to change the rule."

The Senate filibuster rule allows the minority party to prevent the majority from jamming through bills with little or no bipartisan support. It takes a supermajority of 60 senators to end a filibuster and proceed to an up-or-down vote on a bill.

"The most important thing that the filibuster does, in addition to fostering compromise, is give legitimacy to the result of a vote," said Joshua Huder, a senior fellow at Georgetown University's Government Affairs Institute. "If you have buy-in from both parties, it's easier for everyone to accept the outcome."

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Although the filibuster is generally seen as protecting the rights of the minority party, it is also used regularly by senators from the majority.

For example, Huder noted, Sen. Rand Paul, R-Ky., last week blocked Senate leaders from bringing the National Defense Authorization Act to the floor for a quick vote because he wants to force the chamber to vote on his amendments. Paul is a member of a small but vocal coalition of senators who want to restore congressional authority over the use of military force, rather than simply allowing presidents to act.

"The filibuster empowers everybody," Huder said. "That's why (Senate Majority Leader) Mitch McConnell doesn't have the votes to end the filibuster rule even if he wanted to."

McConnell has said repeatedly he doesn't want to kill the legislative filibuster.

"The core of the Senate is the legislative filibuster," McConnell said at news conference last spring. "I'm opposed to (eliminating) it ... I think that's what fundamentally changes the Senate."

McConnell made those comments the same day he led Republicans in changing the filibuster rules as they applied to Supreme Court nominees, allowing the Senate to confirm Justice Neil Gorsuch with a vote of 54-45. When Democrats held control of the Senate in 2013, former majority leader Harry Reid, D-Nev., did away with the filibuster for lower-court judges and Cabinet nominees.

But senators of both parties have guarded the legislative filibuster jealously. In April, 61 senators sent a letter to McConnell urging him to preserve the rule.

"If you abolish the legislative filibuster, the minority party senators would be almost as impotent as the minority party House members, which is pretty darn impotent," said Jack Pitney, a political scientist at Claremont McKenna College in Southern California. "That's the last thing any self-respecting senator wants. There's a reason why House members run for the Senate and not the other way around."

The conventional wisdom is that McConnell and other leaders of the Republican majority don't want to throw out the filibuster rule because they know they will be in the minority again someday.

But Lee sees a less obvious reason for their affection for the rule.

"It gives members of both parties, especially the majority, more freedom from the base of their party," she said. "The leader can say, 'love your ideas, but unfortunately we can't pass them because the other side is going to filibuster them.' It protects leaders; it gives them an out from having to pass a bill they don't really want to pass because they think it's too extreme."

Trump's efforts to keep pounding the Senate to end the filibuster rule, which dates back to the early 1800s, are backfiring, Pitney said.

"We're beginning to see the revenge of James Madison," he said, referring to the father of the U.S. Constitution. "Under the Constitution, the Senate sets its own rules. Senators don't look kindly on kibitzing from presidents."