WASHINGTON (REUTERS) - President Barack Obama said on Friday he will promote his budget director, Sylvia Mathews Burwell, to be health secretary, presiding over the next difficult phase of implementing his healthcare law during the lead-up to the midterm elections.

Ms Burwell, who must be confirmed by the US Senate, will replace Kathleen Sebelius, who was blamed for the disastrous rollout of Obamacare, formally known as the Affordable Care Act, which Republicans plan to exploit as they seek to take control of the Senate in November midterms.