WASHINGTON (AP) — Bernie Sanders has become the clear front-runner in the Democrats’ presidential nomination fight. And his Democratic critics are only now beginning to realize they’re running out of time to stop him. Joe Biden and Pete Buttigieg, among others, dramatically intensified their attacks against the Vermont senator over the weekend. But the cluster of candidates splitting up the anti-Sanders vote is not shrinking. Biden is committed as ever ahead of South Carolina’s Feb. 29 primary, betting that his first victory could slingshot him to the front of the moderate muddle.