WASHINGTON — Beneath the resounding Democratic victories of the past two weeks, tensions have been growing between House Speaker Nancy Pelosi and many new committee chairmen and other members over her aggressive management style and her approach to the war, according to lawmakers and advisers.

Powerful committee chairmen have bridled at the California Democrat’s decision to impose six-year term limits on them. Liberal Democrats say she is being too cautious in confronting President Bush on the war in Iraq. Rank-and-file Democrats say she erred in denying Republicans more say in the early legislation, making the speaker appear autocratic.

And many Democrats complain Pelosi is relying too heavily on a coterie of liberal allies from her home state and Massachusetts to the exclusion of more conservative lawmakers from the Midwest and the South.

The friction will present a growing challenge as Democrats move from the poll-tested, popular items that breezed through the House this month to more difficult legislative ventures, such as efforts to stem global warming, overhaul the nation’s immigration laws, shrink the budget deficit and resolve the war in Iraq. It could hand Republicans a powerful political weapon as they seek to regain power in 2008 by challenging the crop of new Democrats hailing from Republican-leaning districts.

Rep. Marcy Kaptur, D-Ohio, praised Pelosi for guiding through so many popular legislative items so quickly but pleaded for her to develop a more inclusive leadership style.

“If I had any advice, it would be ‘Don’t isolate yourself inside the territory you’re most familiar with,’” Kaptur said last week. “I guess I would say to her, ‘Don’t be isolated by your California experience.’”

Pelosi aides and allies say she is doing her best to be inclusive, and to consult with the strong-willed old bull chairmen, but she must also make room for the new voices that helped the Democrats win back the majority. They said that although that will not be easy, most Democrats will be patient as the new majority settles in.

“I think we suffered the last time the Democrats were in power from too much chairman autonomy,” said Rep. Barney Frank, D-Mass., a Pelosi ally and the chairman of the House Financial Services Committee. “Accusing the speaker of trying to manage public policy is like accusing the fire department of trying to fight fire.”

Pelosi took over the speakership this month after a messy leadership fight in which she backed the losing candidate, Rep. John Murtha (D-Pa.), for House majority leader. She then threw herself into her “hundred-hour” blitz.

In 2 1/2 weeks, the House adopted new rules to curtail the influence of lobbyists and control deficit spending, then passed half a dozen bills to increase the minimum wage, bolster homeland security, fund stem cell research, order the federal government to negotiate lower drug prices for Medicare, cut some student-loan interest rates, and eliminate tax breaks for oil companies to finance alternative-energy research. On virtually every vote, Republicans joined united Democrats in droves.

But backstage, the firm — some say heavy-handed — style Pelosi used to ensure passage of those bills and deal with committee chairmen began to chafe.

Pelosi angered her chairmen and much of the Congressional Black Caucus with her decision to maintain a Republican rule limiting committee chairmanships to six years. Those chairmen and black members have waited years, even decades, to wield power as they patiently abided by the seniority system.

Now, some of the most powerful Democratic chairmen, such as Energy and Commerce’s John Dingell (Mich.), Appropriations’ David Obey (Wis.), and even ideological allies such as Oversight and Government Reform’s Henry Waxman (Calif.), are openly questioning her decision.

Some Democrats were frustrated with her decision not to give Republicans a chance to offer even one amendment on the six bills that passed in the initial spate. Pelosi promised the Republicans will have more input on other matters, but some Democrats say she has unnecessarily ceded the moral high ground.

“As we try to move forward, we have to make sure transparency and cooperation is part of the legislative process,” said Rep. Jim Costa, D-Calif., an advocate of more comity in the House.

On the war front, two Democratic camps have developed. Liberals and antiwar stalwarts such as Murtha, one of Pelosi’s closest allies, want to aggressively use the power of the purse to affect policy, possibly by denying funds for increased troop strength in Iraq. But some senior Democrats and members of the leadership, such as Emanuel and House Majority Leader Steny Hoyer, D-Md., counsel a go-slow approach, in which Democrats start with a nonbinding resolution against the president’s policies, use hearings to build public support for more dramatic action, and gauge voter feelings before legislative action to stop a military buildup in Iraq.

In the most public breach, Pelosi created a special committee dedicated to global warming, infuriating Dingell, whose committee would inevitably lose jurisdiction. Dingell fumed: “These kinds of committees are as useful in relevance as feathers on a fish.”

The move crystallized fears among some moderate Democrats that Pelosi would “policy shop” to produce the legislative outcome she wants, even if that outcome goes against the grain of the moderates’ constituents, several House members said.

At a rancorous closed-door meeting of the Energy and Commerce Committee last week, members of all political stripes backed Dingell and threatened to subject the proposed committee to a public execution on the House floor.

“These are very major blunders on her part,” said a senior Democratic adviser who served for years in the House and spoke on the condition of anonymity for fear of breaching his ongoing relationships. “The general feeling is that she keeps her own political counsel. She doesn’t have any staff who are her eyes and ears and can tell her what’s really going on in the caucus.”

Emanuel conceded some missteps and miscommunication, but he said they are not indicative of larger issues.

Pelosi spokeswoman Jennifer Crider said the speaker has confidence and trust in her committee chairmen but that Pelosi also wants to create new platforms from which fresh voices can be heard. New task forces have been created to get the pulse of members in their 30s, veterans and rural representatives. There is a new black working group to supplement the long-standing Congressional Black Caucus and a faith working group to give a voice to the religious.

Such groups may compete with traditional power centers, but Pelosi will stand by her efforts, aides to the speaker say.