India, Nov. 3 -- Americans vote on Tuesday in midterm elections that will decide control of the House of Representatives and the Senate. But the results will have wider implications. For President Donald Trump, the vote is a referendum on his second term. For both parties, and for the contenders hoping to succeed him, it will shape the race for the 2028 presidential nomination and the direction each takes after Trump. Here is what is at stake for the key players:

Donald Trump

Most indicators suggest that an electoral setback is likely for the 80-year-old commander-in-chief. An unpopular war with Iran, high energy prices and a sustained affordability problem have turned voters against Trump and his party ahead of Tuesday's election. Trum...