President Joe Biden is expected to call for the most sweeping revamp of US benefits since the 1960s as he delivers his first address to a joint session of Congress.
Speaking on the eve of his 100th day in office, the Democrat will pitch $4 trillion (£2.9tn) of spending on child care, education and family leave.
He already passed a $2tn Covid package.
History will also be made as two women sit behind the president for the first time during a speech to Congress.
US Vice-President Kamala Harris and House of Representatives Speaker Nancy Pelosi will both wear masks at the rostrum during Wednesday night's primetime address.