President Donald Trump on Tuesday pressed his Republican colleagues in Congress to unite behind a sweeping tax cut bill, but apparently failed to convince a handful of holdout Republicans that they could still block the package, which covers much of his domestic agenda. In a closed-door meeting on Capitol Hill, Mr. Trump bluntly warned House Republicans not to think about further changes to the mammoth bill. He strongly warned against making it harder for people to get Medicaid. "Stop messing around with Medicaid," Mr. Trump told Republicans, according to one person who spoke on condition of anonymity. He also dissuaded Republicans from seeking further reductions in state and local taxes. But the issue is particularly important to moderate Republicans in high-tax states like California and New York.