Some Democratic incumbents ignored warnings from the party leadership about the tough political climate and didn't "fully prepare" for the campaign season, according to the party's House campaign chief.

Rep. Chris Van Hollen (Md.), chairman of the Democratic Congressional Campaign Committee (DCCC), said Thursday that his party has been preparing for months for a difficult reelection year for incumbents.

"There are a few members who we approached many, many, many months ago to tell them to get their act together, who did not take that advice," Van Hollen said at a breakfast sponsored by the Christian Science Monitor. "We're obviously working very closely now to try and protect even those who did not fully prepare themselves."

Normally safe members such as Reps. Raúl Grijalva (D-Ariz.), Phil Hare (D-Ill.) and Jim Oberstar (D-Minn.) are locked in tight reelection contests this year. All of them hold Democratic-leaning districts; the DCCC has spent money to support Grijalva and Hare.

Van Hollen wouldn’t name the members he thought were caught napping. But he did say Rep. Ike Skelton (D-Mo.) was one example of a member who took the committee's advice and prepared for a tough environment.

Some members, he said, are in tough races because of spending by outside groups.

"What has obviously shuffled the deck in some of these districts is the outside money," Van Hollen said.

He estimated Republican-allied groups were outspending their Democratic counterparts by about a five-to-one ratio.

"It's pouring in. That is something that obviously in some of the races people are having to contend with."

Van Hollen pointed to Rep. Bruce Braley (D-Iowa), who was elected in 2006 and serves as a vice chairman of the DCCC.

"He's a member of Congress who understands campaigns, he fought a hard campaign and yet he’s seeing now $2 million" being spent against him in the district, the Maryland Democrat said. "So we’re going to war in that district's race, despite the fact that I’m confident he's going to win."

Van Hollen noted that the committee was in its strongest position ever to help struggling incumbents.

"I believe the DCCC in 2006 and 2008, today [are] the strongest DCCCs in the history of the organization," he said. "We demonstrated very clearly in the special elections in the past that we know how to win races."