U.S. Senators Elizabeth Warren and Bernie Sanders defended their turf on the progressive end of the Democratic race for President on Tuesday night in Detroit.

“They got a lot of criticism from the other candidates, including many who we might call the second-tier candidates,” said Emporia State political scientist Michael Smith. “At least second-tier for now.”

Making a name for yourself on that crowded of a stage isn’t easy, though.

“For someone like a [U.S. Rep John] Delaney or a [Montana Governor Steve] Bullock, who is maybe not as well known outside their own home state or home district, you try to raise your profile by differentiating yourself from someone like Sanders and Warren, you’re also raising the stature of Sanders and Warren.”

The issue that looks to be a dividing line for the Democrats is how quickly healthcare can progress.

“It really is coming down to this Medicare for All, versus a plan that expands access, while people that have private health insurance who choose to do so keep that insurance,” said Smith.

Smith notes that some candidates are raising concerns that Medicare for All would give union members and retirees worse benefits than those they have gained through collective bargaining and union support is vital in a general election, particularly in the swing states that went for Donald Trump in 2016.