House Speaker John Boehner’s still-unfiled lawsuit against President Barack Obama for exceeding his constitutional power is in more trouble.

For the second time in two months, a major law firm has ceased work on the lawsuit, sources say.

Attorney Bill Burck and the Quinn Emanuel firm halted preparations for the proposed suit in recent weeks, according to two sources familiar with the situation. Last month, the lawyer originally hired to pursue the case, David Rivkin of Baker Hostetler, made a similar abrupt exit.

A spokesman for Boehner declined to discuss the status of the House’s relationship with Burck and Quinn Emanuel. However, spokesman Kevin Smith said Wednesday evening that House leaders are considering having the lawsuit filed by lawyers already on the House payroll.

(Also on POLITICO: 5 most suspenseful House races)

“The litigation remains on track, but we are examining the possibility of forgoing outside counsel and handling the litigation directly through the House, rather than through law firms that are susceptible to political pressure from wealthy, Democratic-leaning clients,” Smith said.

Boehner’s office also suggested the suit, which planned to challenge Obama’s failure to implement aspects of his health care reform law, could be broadened if Obama goes forward, as promised, with plans for executive action on immigration.

“We are also closely following what the administration does on executive amnesty, and the possible impact that could have on the litigation strategy,” Smith said.

(Also on POLITICO: Feinstein: 'I have no idea what I'm going to be doing in 2018')

A House leadership aide said if the immigration issue is litigated it would be in addition to, and not in lieu of, challenging Obamacare.

Burck declined to comment about the status of the litigation. The contract he signed with the House last month bars his firm and its employees from speaking to the media about the litigation without prior approval from the House General Counsel Kerry Kircher.

Moving the litigation in-house could also help quiet a regular line of criticism from Democrats: namely that Republicans are wasting taxpayer funds on a lawsuit against the president. Lawyers at both firms were to be paid up to $500 an hour for a total of up to $350,000 for the first stage of the case.

(Also on POLITICO: The Democrats' Royal Families)

“The American people are fed up that their hard-earned taxpayer dollars are being used to solve John Boehner’s political problems. In the words of one legal scholar, this lawsuit continues to be an embarrassing loser for Speaker Boehner,” said Drew Hammill, a spokesman for House Minority Leader Nancy Pelosi.

Rivkin’s firm withdrew in September after health-care-related clients pressured the firm to back out of representing the House in the Obamacare-related suit. Two sources told POLITICO in recent days that a similar scenario played out with Burck’s firm, with clients bringing pressure to get the firm off the case.

Boehner first floated the idea of a lawsuit against Obama in June, suggesting that it could address a range of areas in which the president had overstepped his constitutional authority.

“On matters ranging from health care and energy to foreign policy and education, President Obama has repeatedly run an end-around on the American people and their elected legislators, straining the boundaries of the solemn oath he took on Inauguration Day,” the speaker said in a letter to members. “Everywhere I go in America outside of Washington, D.C., I’m asked: when will the House stand up on behalf of the people to stop the encroachment of executive power under President Obama? We elected a president, Americans note; we didn’t elect a monarch or king.”

The speaker later suggested that the planned lawsuit would focus on Obama’s repeated delays of the employer mandate under Obamacare, despite the fact that Republicans strongly oppose that mandate. However, a resolution that formally passed the House in July authorized the filing of a suit focusing on any aspect of the health reform law known as the Affordable Care Act.

(Also on POLITICO: Obama, Bibi 'chickensh—' uproar)

A new resolution and a new vote would likely be required if the suit were expanded to matters other than Obamacare, such as immigration.

Lawyers involved in discussions about the planned lawsuit said they originally expected it to be filed in September, but POLITICO reported last week that it was unlikely the case would be filed before the election. Some cited the turmoil on the legal team, while others said they suspected a decision to deliberately lower the profile of the lawsuit in advance of the midterms.

In addition, a Congressional Research Service report completed in September and published Friday by two liberal lawyers in the Washington Monthly indicated that a suit focusing on delayed enforcement of some aspects of Obamacare was likely to get little traction in the courts.

Some Democratic lawyers and a few Republican attorneys have said they believe it’s possible no suit will ever be filed.

While it’s surprising that two different outside law firms could have cold feet about a case, the House has previous experience with such problems.

In 2011, Atlanta-based law firm King & Spalding backed out of a contract to represent the House in litigation defending the Defense of Marriage Act. Gay rights activists pressured King & Spalding client Coca-Cola to urge the firm not to handle the case.

King & Spalding partner Paul Clement, a former solicitor general, quit the firm amid the dispute. He started a new firm and argued — ultimately unsuccessfully — on behalf of the House on the DOMA issue at the Supreme Court.