Continued from page 1

The deal that exchanged five Taliban guerrillas for Army Sgt. Bowe Bergdahl’s return, however, could be a more ripe target, Mr. Fisher said, especially since both political parties have been critical of the president for not giving Congress the required 30 days notice to release prisoners from the detention facility at Guantanamo Bay, Cuba.

“That to me would be action in court that has merit,” he said. “If both chambers are agreed, as with the 30 days notice, it’s a stronger case than when the two chambers are divided.”

Mr. Boehner, in his memo, said when he travels outside Washington, voters regularly ask him to stand up to Mr. Obama’s use of executive authority.

He said allowing a president to unilaterally reinterpret laws sets a dangerous precedent that shifts power from Congress and amounts to “giving the president kinglike authority.”

He demurred when asked Wednesday whether this was the first step toward impeaching Mr. Obama.

Minority Leader Nancy Pelosi, California Democrat, said that Mr. Boehner is only pursuing the lawsuit to look like Congress is doing something and hopes he takes the more mature approach to drop the lawsuit.

“There really needs to be an adult in the room of the Republican caucus. I hope the speaker is that adult,” she said.

Mrs. Pelosi said that instead of suing the president, Republicans should be working to pass the legislation that she says is important to the American people, including the voting rights act, immigration reform and an extension to unemployment insurance.

However, Democratic fundraisers quickly moved to take advantage of the Boehner letter in appeals to their base. The House Majority PAC called the letter “a new low” in an online solicitation for funds that also accused Mr. Boehner of “caving in to pressure from the right and suing President Obama.”