Regardless of whether Democrats keep the White House or Republicans retake the presidency, their ability to actually pass their agenda through Congress will depend on which party controls the U.S. Senate. And right now, both parties are going all-in on a state former President Donald Trump easily won in both 2016 and 2020. According to Semafor, Sen. Jon Tester (D-Montana) is in the midst of the most heated Senate contest in the country, and millions of dollars are being spent both on his behalf and against him. While Tester is the sole remaining Democrat holding any statewide office in the Big…