Katie Packer, another veteran of the Romney campaign who is now leading an anti-Trump super PAC that’s spending heavily in the early states, is worried that Republicans are running out of time, especially given his potential strength in a number of southern states that vote on Super Tuesday.

“Trump is by no means a runaway train. There has never been a year like this with so many legit candidates,” Packer said. “And Trump has the highest negatives of any frontrunner in either party—the highest number that actively don’t want him. As soon as the race gets down to two he will fall. Needs to happen before March 15.”…

John Kasich, by virtue of finishing second in independent-heavy New Hampshire, is heading south too, although he’s not a great fit for South Carolina, which is shaping up to be a four-way fight between candidates who all have inherent advantages there: Rubio’s team has the most experience in the state, Bush has a family connection that dates back decades, Cruz and Trump have appeal to the state’s evangelical and blue collar conservatives—and all four have plenty of money.

Should these four candidates continue to divide the anti-Trump vote in the next several contests, and with Kasich ready to patiently seek delegates in Midwestern states when the primary fight broadens out, it’s possible the ongoing circular firing squad among several establishment candidates ensures that Trump is the last Republican standing—a scenario that only fuels further speculation about a brokered convention.