What are the 'midterms' and why is Trump risking his margin to govern?

The midterm elections in the U.S. are crucial as they determine the balance of power in Congress. On November 3, all members of the House of Representatives and a third of the Senate will be elected. The outcomes will significantly impact Donald Trump's ability to advance his agenda. If Democrats gain control of either chamber, they can obstruct Republican legislative initiatives. Winning the Senate would also allow them to block presidential appointments, including judges and key officials, as well as influence numerous state governorships and referendums across the country.