DORAL, Fla. — Democrats in Congress are considering forcing a showdown over the debt limit to rein in President Donald Trump’s vast plans to reshape the U.S. economy and remake the federal government. For 30 years, Republicans have used the threat of a national default to make Democrats negotiate over GOP demands. But as America hurtles once again toward a potential debt crisis, Democrats see an opportunity to turn the tables to cut off Trump’s agenda and take the debt limit off the table in future legislative battles. Last week, the national debt hit the legal limit of $31.4 trillion....