Barack Obama’s campaign manager assured House Democrats Wednesday that the party’s presumptive presidential nominee wants their input and will work seamlessly with them in the fall to produce a bigger House majority.

After David Plouffe addressed the caucus, Rep. Jan Schakowsky, D-Ill., said, “It was a brilliant presentation of ways to get to 270 electoral votes and how the presidential race intersects with House races, and how much synergy there will be.’’

In recent weeks, there has been some behind the scenes grumbling among congressional Democrats that the Obama campaign has not done enough to reach out to them for input. But Schakowsky, an early Obama backer, said, “What people are waiting for is marching orders. There is an organizational period but every member is important to the campaign.’’

Obama has assembled a congressional liaison team headed by longtime House aide Phil Schiliro, who attended Wednesday’s session.

Another longtime Obama backer, freshman Rep. Paul W. Hodes, D-N.H., said that in his state the Obama campaign has already started coordinating its activities with him and another freshman, Rep. Carol Shea Porter. “Both Shea Porter and I endorsed Obama. You can see the strength of organization that the campaign has in New Hampshire and the degree of coordination we are already seeing in Washington and in New Hampshire,’’ Hodes said.

In his presentation, Plouffe pointed to 18 battleground states, some of them non-traditional Democratic targets such as Colorado and Montana, where Obama will make a concerted effort against Sen. John McCain of Arizona, the prospective Republican nominee. Plouffe also told the members that the Obama effort will emphasize its grassroots effort, driven by 1.8 million donors and some one million volunteers already signed up.

Rep. John B. Larson of Connecticut, vice chairman of the House Democratic Caucus, said Plouffe emphasized the need for lawmakers, particularly from safe districts in safe Democratic states, to join the effort to get out the vote in areas that are up for grabs. “We’re going to win the old fashioned way, on the ground,’’ Larson said.

“We’re going to have to work. We’ve got a fight on our hands,” Larson said.

Even though many polls show Obama with a lead over McCain and Democrats expect to win a bigger majority in Congress, lawmakers said there is no danger of overconfidence heading into the party’s late-August convention in Denver or the fall campaign.

“After the last two presidential election cycles, I don’t think anybody feels overconfident,’’ said Rep. Diana DeGette, D-Colo.

Rep. Allen Boyd, D-Fla., said, “How can we be overconfident after we’ve gotten our butts kicked in the last two elections? The Republicans are very good at messaging and such.’’

Boyd said Obama is doing well in Florida, one of the 18 targeted states, “I think it’s good. But there’s a long way to go,’’ he added.

Rep. Jackie Speier, D-Calif., agreed but said the poll numbers for Obama and congresisonal Democrats “are pretty startling. We’re blowing McCain out of the water.’’

“The numbers are dramatic but the Obama campaign is playing it as if they’re in a horse race. Not only in the states they’ve targeted but in states we haven’t traditionally targeted.’’