"I am," he told reporters at a weekly briefing on Capitol Hill. His intention to sue the administration was reported Tuesday.
Asked if his plan could lead to impeachment proceedings in the House, as some have called for, Boehner demurred.
"This is not about impeachment," he said. "This is about faithfully executing the laws of our country."
The speaker declined to provide details about which executive actions he intends to challenge in court.
"When I make that decision, I'll let you know," he said, adding that "when there is conflicts like this between the legislative and administrative branch, it's our responsibility to stand up."
"We've seen clearly an effort to erode power of the legislative branch," he added.
White House press secretary Josh Earnest dismissed the move on Wednesday,telling reporters that "most Americans wouldn't support" a "taxpayer-funded lawsuit against the president of the United States for doing his job."
Often stymied by a recalcitrant Congress, President Barack Obama declared 2014 a "year of action" and issued executive orders on immigration, the federal minimum wage and federal pay discrimination. His Environmental Protection Agency further plans to unveil unprecedented regulations to curb greenhouse gas emissions from coal-fired power plants.
Obama's executive actions have prompted some to call for his impeachment. The South Dakota Republican Party did so last week, when it passed a resolution citing in part the proposed EPA regulations. Rep. Lou Barletta (R-Pa.) claimedthat the House could "probably" impeach Obama if the matter were brought to the floor.
UPDATE: 2:51 p.m. -- In a memo addressed to his colleagues on Wednesday, Boehner officially announced his plans to introduce legislation in July that would authorize the House General Counsel to sue the Obama administration and "compel" the president to fulfill his oath of office to enforce existing law.
"If the current president can selectively enforce, change or create laws as he chooses with impunity, without the involvement of the Legislative Branch, his successors will be able to do the same," Boehner wrote in the memo. "This shifts the balance of power decisively and dangerously in favor of the presidency, giving the president king-like authority at the expense of the American people and their elected legislators."
It's still unclear which executive actions Boehner means to challenge, but the memo names a few areas, including health care, energy, foreign policy and education, that the president has "repeatedly run an end-around on the American people."