House Republicans officially gave Speaker John Boehner (R-OH) their seal of approval on Wednesday to sue President Barack Obama, marking the first time in U.S. history that a chamber of Congress has endorsed a lawsuit against a president.

The House adopted the resolution by a vote of 225-201. Five Republicans joined a unanimous Democratic conference to vote against the measure. They were Reps. Thomas Massie (R-KY), Walter Jones (R-NC), Paul Broun (R-GA), Steve Stockman (R-TX) and Scott Garrett (R-NJ).

The resolution authorizes Boehner to challenge Obama in court for exceeding his authority by unilaterally delaying deadlines under Obamacare. Although he has said he’ll target the one-year delay of the health care reform law’s employer mandate penalties, the text of the GOP resolution gives the Speaker room to legally challenge implementation tweaks to other provisions of the law.

“This isn’t about Republicans and Democrats. It’s about defending the Constitution that we swore an oath to uphold,” Boehner said. “Are you willing to let any president choose what laws to execute and what laws to change? Are you willing to let anyone tear apart what our Founders have built?”

The move comes as Boehner feels elevated pressure to wage new battles against Obama from confrontation-hungry conservatives. It’s a politically awkward one for his party given that Republicans despise the employer mandate, and have voted to eliminate and delay it. Republican aides say they chose the issue for legal reasons as they think it gives them the best chance of victory in court.

“Republicans want to sue the president for not enforcing a law they want to repeal,” said House Minority Whip Steny Hoyer (D-MD). “It is wrong. It is a waste of time. It is a waste of money. It is a distraction from the important issues so important to our people. This lawsuit is nothing more than a partisan bill to rally the Republican base.”

Democrats are aggressively fundraising off the planned lawsuit, portraying it as a precursor to impeachment. They’ve boasted about raising millions of dollars from donors recently over the two issues. Boehner has repeatedly insisted he has no plans to impeach Obama, describing it as a Democratic “scam.” The White House responds that House Republicans were discussing the issue long before Democrats mentioned it, and that GOP leaders also vowed they wouldn’t shut down the government before that happened last fall.

Boehner faces an uphill battle in court. The first big question is whether he can achieve “standing” which requires proving a material injury to the House. Legal experts say that’s a very difficult task because no lawsuit emanating from members of Congress against the president has ever achieved standing in court. The next question, if the courts grant standing, is whether the lawsuit has merit to succeed. Republicans may have better luck on this question, experts say, as Obama’s unilateral decision to delay a statutory deadline is arguably problematic from a legal standpoint.

Progressives and some conservative legal minds warn that if the lawsuit succeeds, it would declare open season for the executive and legislative branches to sue each other over any legal disagreement and empower judges to resolve such disputes.