By Andrew Goudsward, David Morgan and Doina Chiacu

WASHINGTON/ANCHORAGE, Alaska, Nov 1 (Reuters) - Two days before Tuesday's midterm elections, President Donald Trump's Republicans got an unexpected boost in Michigan with an endorsement from a prominent Democrat, while suffering a setback in Alaska when a federal judge dismissed a legal challenge.

US Representative Haley Stevens, who lost Michigan Democrats' Senate primary to Abdul El-Sayed in ‌a bitterly contested race, on Sunday publicly backed Republican candidate Mike Rogers, threatening to exacerbate divisions in a state viewed as crucial to Democratic hopes of retaking the US Senate.

"I don't belong in Abdul's ‌campaign," Stevens said in a video posted to social media.

Thirty-five Senate seats and all 435 House of Representatives seats are on the ballot on Tuesday. Republicans hold narrow majorities in both chambers. Polls show Democrat...