Still, Van Hollen promised a top recruit for the inevitable special election to replace McHugh, who was nominated to be Army Secretary by President Obama today.
"That seat has been a traditional Republican seat," Van Hollen told ABC's "Top Line" in a bid to set expectations for Democrats' competitiveness in the district. "Clearly, it's an uphill battle because there's an entrenched Republican infrastructure there."
Still, Van Hollen professed optimism in Democrats' odds to take over the seat.
"As we saw in New York 20, we can compete in those districts," he said, alluding to the special election victory of Rep. Scott Murphy (D-N.Y.) earlier this year over state Republican leader Jim Tedisco.
The leader of Democrats' midterm campaign efforts said that 2010 would be a "tough year" for Democrats if historical patterns of the party holding the White House losing seats in Congress holds true.
"I strongly believe that the best defense is a good offense," he said. "Right now, we're focused on making sure our incumbents from tough districts are in a strong position. At the same time, we're out there recruiting candidates throughout the country."