WASHINGTON (Reuters) - The chairman of the U.S. Senate health committee on Tuesday urged U.S. President Donald Trump to drop his threat to cut government subsidy payments to insurers that make Obamacare plans affordable and allow the payments through September. Republican Senator Lamar Alexander said his committee would begin bipartisan hearings on stabilizing the individual health insurance market the week of Sept. 4 and urged fellow lawmakers to fund the cost-sharing subsidies for one year. 