The nation’s four big television networks, determined to overcome a stinging rebuke in the House last week, are ramping up a coordinated lobbying campaign to block an effort to rein in their power.

Disney-owned ABC, General Electric-owned NBC, Viacom-owned CBS and News Corp.’s Fox have jointly hired Cassidy & Associates — a firm with strong ties to Congressional appropriators — to help kill a provision in a spending bill that would limit their reach.

The four companies are also mulling a public relations campaign for the August recess to make the case on Capitol Hill and in key Congressional districts that the networks must be allowed to grow to compete with cable companies and satellite broadcasters.

“All hands are on deck,” said Mike Reagan, News Corp.’s top Washington lobbyist. Added NBC’s Bob Okun: “We are working hard to educate House Members and Senators.”

The unified lobbying battle in Washington comes just months after the last of the networks, ABC, left what once was the network’s main lobbying arm, the National Association of Broadcasters. The networks left NAB because they thought the association too often sided with the smaller affiliates over their larger competitors.

The tension bubbled over when NAB took the lead opposing the Federal Communications Commission’s plans to relax the media-ownership rules even though the networks supported the changes.

The four networks have since held informal talks about forming their own lobbying coalition in Washington or attempting to overhaul NAB. NAB’s board of directors will be in town today for a special meeting to discuss the future of the trade association.

The new effort by the networks could serve as a trial run for a more permanent partnership down the road, said sources close to the issue.

In the near term, the measure of their success will be clear: Defeating legislation that would strike down a FCC plan to permit television networks to own more local stations.

The FCC voted last month to raise the network’s national audience cap to 45 percent of households from 35 percent.

But a large, bipartisan group of lawmakers — sparked by public fears of having a few giant corporations controlling the nation’s news media — have launched efforts in both chambers to roll back the FCC’s move, in effect reinstating the cap.

Last week, the House approved a measure by Rep. David Obey (D-Wis.), despite the opposition of the entire House Republican leadership and a veto threat from President Bush.

Senate Appropriations Chairman Ted Stevens (R-Alaska) and Sen. Fritz Hollings (D-S.C.) plan to add a similar amendment this week to legislation funding the FCC.

Even before last week’s vote in the House, the networks were resigned to the fact that both chambers would probably pass the legislation.

In fact, Republican leaders made no attempt to take out the amendment after it was added to the Commerce, State, Justice funding bill on a 40-25 vote earlier this month in the House Appropriations Committee.

Instead, they will attempt to defeat it in a House-Senate conference by demonstrating that they have enough votes in the House to sustain a presidential veto.

Before the House vote, Bush aides summoned top network lobbyists to the White House and instructed them to round up votes from one-third of the House — the number needed to sustain a veto.

For help, the networks turned to Cassidy & Associates. The effort will be led by Gregg Hartley, a former top aide to House Majority Whip Roy Blunt (R-Mo.), and Steve Seale, a former aide to Sen. Trent Lott (R-Miss.).

The networks already boast a formidable lobbying team costing millions of dollars and involving some of the top names on K Street. Hartley and Seale are working with Rep. Chris Cannon (R-Utah) to find signatures for a letter supporting the networks.

“We want to have the signatures to show the president that he has support for the veto,” said Meghan Riding, a spokeswoman for Cannon.

The networks have gathered 50 signatures so far and hope to cross the needed 144 signature mark after the August recess.

Another strategy under consideration is adding newspaper-television cross-ownership restrictions to the legislation, a move that could cause the measure to collapse under its own weight.

In the meantime, the lobbyists for the networks believe that defeating the legislation could have far-reaching consequences for the industry’s role in Washington by prodding changes at NAB.

It is unlikely that the networks will “actually form our own association with offices and staff and health benefits and retirement plans,” said Preston Padden, head of ABC’s Washington operations. “But my personal hope is that out of all this disarray, we are able to get the NAB put back together as a unified body.”