Richard Nixon, who ran 5 times for president or vice president, said he ran to the right to win the Republican nomination, but then back toward the center in the general election.
In 2004, George W. Bush and Karl Rove reinvented presidential campaigns. Discovering that undecided independent voters had shrunk from 20-plus percent to single digits, they concentrated on turning out their own base of voters and it worked. Later campaigns have followed this sometimes ugly, but effective strategy.
Now the Democrats face a dilemma. Their early energy was all from far left Bernie Sanders, Elizabeth Warren and Kamala Harris.
But not so fast, as late entry Joe Biden is more moderate, though he is being pushed left on issues such as abortion and climate change.
Persuading the middle better suits Biden, but Democrats may demand a hard left turn.