The US House of Representatives has approved a Republican plan to file a lawsuit against Barack Obama for allegedly exceeding his constitutional powers.
The lawsuit relates to the way the US president enforced the 2010 health care law.
Democrats say itis a campaign-year stunt designed to draw conservative voters to the polls in congressional elections in November. They also say it may be a prelude to an effort to impeach Obama, a suggestion which top Republicans say is groundless.
Republicans say Obama has gone too far in selectively enforcing parts of the health care overhaul, the signature legislation of his presidency, such as by delaying the requirement that many employers provide health insurance for their workers.
They say they are protecting the constitution's division of powers. Republicans have not laid out a timetable for actually filing the suit.
The House vote on Wednesday was 225 to 201. No Democrats voted for the plan.
Speculation about impeachment of Obama has been popular among conservative activists, despite House Speaker John Boehner's dismissal of the idea. Democrats have capitalised on the speculation, sending fund-raising pleas to their own supporters warning that Republicans are out to impeach Obama and ruin his presidency.
Republicans, who are expected to keep their House majority after November's elections and hope to gain control of the Senate, say Obama has enforced laws as he wants to, dangerously shifting power to the presidency from Congress.
Obama said the vote to file a lawsuit is taking away from time they could be spending on issues important to the American people. He described the measure as a "political stunt" and said he took actions on his own because Congress isn't doing anything to help him.
Every Republican opposed Obama's health care overhaul.
Republicans say Obama has illegally changed the law by using executive actions that don't require Congress approval. The White House and Democrats say he's acted legally and within his powers as chief executive.