There's no greater insult in GOP circles than to compare someone to French President Jacques Chirac.

But that's exactly what some Republicans are doing in support of President Bush's $726 billion tax-cut proposal — the centerpiece of his economic program. As Operation Iraqi Freedom winds down, Bush has been stumping for his tax cuts again, saying he would be willing to accept a $550 billion package.

Some ads are suggesting that Bush needs strong allies at home — just as he did abroad — when it comes to passing the proposal, which Senate Republicans have cut almost in half. Chirac and his diplomatic crew, particularly French Foreign Minister Dominique de Villepin, were anything but friendly toward Washington during the White House's effort to win U.N. backing for forceful disarmament of Iraq.

It's the "so-called Republicans" versus the "New York City elitists" in rival GOP ads that expose a growing rift between the party's conservatives and moderates over Bush's tax cut proposals.

The Club for Growth, a conservative, tax-cut advocacy group, on Saturday will kick off a series of ads in Columbus, Ohio, and Portland and Bangor, Maine, aimed at two moderate GOP senators, Ohio's George Voinovich and Maine's Olympia Snowe.

Their opposition effectively thwarted party leaders' efforts to win approval of a larger tax cut when the April 11 Senate vote on the measure lasted late into the night.

The ads equate the actions of these "so-called Republicans" with the obstacles raised by France to the U.S. war effort in Iraq. French led a series of countries opposing armed intervention, including China, Germany and Russia.

In one ad, Voinovich is pictured next to a waving French flag.

"These Franco-Republicans are as dependable as France was in taking down Iraqi dictator Saddam Hussein," Club for Growth President Stephen Moore said in a statement.

On Sunday, the Republican Main Street Partnership, representing some 65 moderate GOP lawmakers and governors, plans to counterattack with a newspaper ad in Portland defending Snowe and characterizing the Club for Growth as "misinformed New York City elitists."

"No one who stands her ground while crafting a budget should have her patriotism challenged," reads the ad. The Partnership also plans to run TV ads in Maine for Snowe, one of its members, in the next few weeks.

Sarah Chamberlain Resnick, the Partnership's executive director, said the Club for Growth was trying "to weed out Republicans who don't meet their litmus test from serving in both Congress and the Bush administration." She said the Club's ads were tasteless.

But Moore said his group was questioning the economic judgments of Snowe and Voinovich, not their patriotism.

"This is really an important party loyalty vote," he said in an interview. "We should have total party unity on tax cuts.

"We're very loyal to the President and his economic agenda. The people who have divided the party are precisely Olympia Snowe and George Voinovich."

Rifts among the GOP on the issue became glaring last week when the House and Senate agreed to a budget blueprint for fiscal 2004 that outlined a $550 billion tax cut over 10 years.

That was less than the $726 billion Bush requested but still too high for Snowe and Voinovich, who joined Democrats in questioning big tax cuts at a time of war and rising budget deficits. They refused to allow more than $350 billion in the budget's tax cut plan.

Senate Finance Committee Chairman Charles Grassley, R-Iowa, assured Snowe that he and Senate Majority Leader Bill Frist of Tennessee would not support a larger cut.

"There would be no budget and no growth package without our agreement," Grassley said, expressing regret that the reductions would not be larger.

The Senate passed the $2.27 trillion federal budget that included the $350 billion ceiling last Friday on a vote that required Vice President Dick Cheney to break a 50-50 tie. Republicans hold a slim 51-49 margin in that chamber.

"Logic prevailed," Voinovich said.

The Senate won't even have room to include the president's proposal to reduce taxes on corporate dividends unless its cost is offset by increasing taxes or closing tax loopholes.

House Republicans were seeing red after their Senate colleagues had cut a deal without letting their House counterparts in on it.

"This goes right to the heart of our ability to work together," said House Majority Leader Tom DeLay, R-Texas. "It's very disturbing."

The House passed a budget allowing cuts of as much as $550 billion through 2013. Last month, it agreed to all of the entire $726 billion but now, after the Senate's vote, House tax-writers will have to accept smaller reductions.

Bush wants Congress to act on his proposal as soon as lawmakers return from their two-week Easter recess.

While Congress is away from the Hill, Bush and nearly 30 other administration officials are fanning out to 30 states and nearly 50 cities to sell the president's tax cuts.

In last year's election, the Club for Growth unsuccessfully backed a Republican challenger to seven-term Maryland moderate Wayne Gilchrest and it is now promoting the campaign of Rep. Pat Toomey to unseat moderate Pennsylvania Republican Sen. Arlen Specter.

It is also urging conservative Rep. Jeff Flake, R-Ariz., to challenge Sen. John McCain, another Partnership member and frequent critic of White House policies.

The budget is a non-binding resolution used by Congress to outline tax and spending policy. It projects deficits will peak next year at $385 billion, then decrease gradually until a $10 billion surplus is reached in 2012.

It permits the spending controlled by Congress to grow less than 3 percent next year, to $785 billion. More than half that money — $400 billion — will go to defense.

And Bush will spend whatever political capital and muscle is needed to persuade Congress to give him the biggest-possible economic-stimulus bill.

At a meeting of about 80 high-level business lobbyists and other tax-cut supporters at the U.S. Chamber of Commerce on Wednesday, White House political adviser Karl Rove "said the president was going to go all the way with this," a business leader who attended the closed-door session told the The Washington Times.

"I think you will see the beginning of a full-court press take place," Bruce Josten, chief lobbyist for the chamber, told the Times.

Bush's tax plan includes: the acceleration of tax cuts scheduled to take effect in 2004 and 2006 to make them effective this year; the tripling of small business expensing limits; increasing the Alternative Minimum Tax exemption; the acceleration of reductions in the marriage penalty tax; increasing the child tax credit; and abolishing the double taxation of corporate dividends.

Fox News' Major Garrett and The Associated Press contributed to this report.