Washington — The November ballot in Texas is now set, after a four-term incumbent Republican senator lost to a Trump-endorsed challenger in Tuesday's primary runoffs. Meanwhile, Texas Democrats are angling to win their first Senate race since 1988.The Senate race was just one storyline on Tuesday night, as many downballot primary races highlighted larger themes seen throughout the country for both Democrats and Republicans. Here are some of the top takeaways from Tuesday's election:Power of Trump's endorsement Republican Sen. John Cornyn fell to Texas Attorney General Ken Paxton in a GOP primary runoff, losing the Senate seat he has held for 24 years by a 27-percentage-point margin.One decisive factor in the race: A week beforehand, President Trump backed Paxton.While Cornyn frequently stressed on the campaign trail that he has voted with Mr. Trump over 99% of the time, the longtime Texas senator questioned Mr. Trump's electability after his first term in office. In his endorsement of Cornyn's opponent, Mr. Trump said "John Cornyn is a good man, and I worked well with him, but he was not supportive of me when times were tough." By comparison, the president called Paxton a "true MAGA Warrior" and stressed his loyalty.Many establishment Republicans had seen Cornyn as a stronger candidate to take on the Democratic nominee, Texas state Rep. James Talarico, in the general election. Talarico did not face a runoff on Tuesday after he won a majority of the vote in the first round of the primaries in March.