ATLANTA — Pete Buttigieg’s rise in the Democratic presidential primary makes him a prime target at Wednesday’s debate as the four candidates now bunched at the top seek to distinguish themselves with less than three months until voting begins.

The 37-year-old mayor of South Bend, Indiana, has gained significant ground in recent months in Iowa, which holds the nation’s first caucuses on Feb. 3. But with top-tier status comes added scrutiny, as the other front-runners discovered in four previous debates throughout the summer and fall.

Former Vice President Joe Biden had to swat back criticism of his past work with segregationist Senate colleagues and his support of some unpopular Obama administration policies.