As his Republican rivals sparred onstage in California at their second primary debate, Donald Trump was in battleground Michigan Wednesday night working to win over blue-collar voters in the midst of an autoworkers’ strike. Trump in his speech lambasted President Joe Biden and his push for electric cars a day after Biden joined striking workers on the picket line in Detroit. The dueling appearances had the feel of the opening salvo of the 2024 general election, which is increasingly looking like a rematch between Trump and Biden, even though voting won't begin until next year.