US President Joe Biden and former president Donald Trump are poised to move much closer to winning their party’s nominations during the biggest day of the primary campaign on Tuesday, setting up a historic rematch that many voters would rather not endure. Super Tuesday elections are being held in 16 states and one territory – from Alaska and California to Vermont and Virginia. Hundreds of delegates are at stake, the biggest haul for either party on any single day. While much of the focus is on the presidential race, there are also important down-ballot contests. California voters will choose c…