[cnn-photo-caption image= http://i.cdn.turner.com/cnn/2008/images/04/08/art.vanhollen.gi.jpg caption="Van Hollen is chairman of the DCCC."](CNN) - The top Democrat charged with helping his party maintain control of the House in 2008 warned Tuesday congressional candidates could suffer if the Democratic presidential race turns overly negative.
Speaking at a press briefing with reporters, Democratic Congressional Campaign Committee Chairman Chris Van Hollen predicted the Democrats will pick up House seats in November, but said the ongoing contest between Hillary Clinton and Barack Obama remains a "variable."
"We've seen the energy and excitement in the early Democratic primaries, and the only thing that could hurt or cut back on that is if the Democratic primary gets so divisive that it's difficult to patch it up and heal the wounds in time to be together in November," said Van Hollen, who has not endorsed either candidate.
"We need to make sure that both candidates stay positive so you don't leave lasting wounds that will depress in anyway that kind of energy and enthusiasm," he added. "I don't think we are at that point. I do think there is a danger of reaching that point."
At the same briefing, Clinton backer and Democratic Senatorial Campaign Committee Chairman Chuck Schumer sounded a less dire tone, saying the hotly-contested race will benefit the party come November.
“Each is getting to refine their message and battle test their campaigns in this primary," he said. "I don't think any damaging blows have been landed by one or the other, and damaging to the general election, and I think both are very strong candidates."