Their efforts moved into higher gear this week with the entry of Florida Gov. Ron DeSantis into the race. His glitch-filled launch on Twitter Spaces drew widespread mockery from Trump and other Republicans. The Biden campaign moved swiftly too, trolling DeSantis with a tweet to its own fundraising page (noting that “this link works”) and buying Google ads for searches like “DeSantis flop” and “DeSantis disaster.” But the campaign and, in particular, the DNC also welcomed DeSantis to the fray with more substantive broadsides. They unleashed a series of attacks and opposition research dumps, highlighting a number of his positions...