US President Barack Obama hosts a forum Friday on women and the economy, as aides warn of a "devastating" impact on the key voting bloc if the Supreme Court overturns his health care law.

The White House said the forum would "examine the ways in which the administration has worked to ensure women's economic security and create jobs for women, through all stages of life."

The event is taking place at a time when Obama has pulled out to a big lead according to opinion polls among women voters over his most likely Republican presidential rival, Mitt Romney.

It also comes several days after the president warned the nine justices of the conservative majority Supreme Court not to overturn his landmark health reform law, following three days of combative court arguments last week.

The top US court is expected to rule in June on whether the law is constitutional, a judgment that could have an explosive impact on the campaign ahead of the November 6 presidential election.

The law, known as the Affordable Care Act, expands access to health care for millions of Americans and prevents insurance firms refusing care to patients with pre-existing conditions among other provisions.

A senior Obama administration official said Thursday that if the law is repealed, women would find it harder to have their specific health needs addressed.

"It would be devastating for women," one official said on condition of anonymity.

Another official said that a Republican budget passed by the House of Representatives would also "be disproportionately harmful to women" reflecting Obama's desire to lock in his lead among women voters as the election campaign speeds up.