A wave of negative television advertisements that Senator Clinton was expected to unleash on Senator Obama this week will likely be shelved until Super Tuesday next month in light of the changed dynamics of the Democratic race following her win in New Hampshire, political strategists and ad consultants said yesterday.

“I would be very wary of being the first to draw blood,” a Democratic ad maker not affiliated with any presidential campaign, John Lapp, said. “You have such an advantage doing the response, being able to call the other person negative, and then you go ahead and lower the boom.”

Mr. Lapp, who advised Richard Gephardt in his 2004 presidential bid, said he expects the next round of ads from Mrs. Clinton and Mr. Obama to point up each other’s flaws only in an indirect way. “For the near future, they’ll be positive, aspirational, and at most have very collegial comparatives with no names mentioned,” he said. The ad maker said Mr. Obama’s ads will likely talk about getting away from “the old politics,” while Mrs. Clinton’s will probably allude to the dangers of inexperience.

Unions and political groups are likely to be the first to unveil hard-hitting spots in Nevada and South Carolina, if anyone chooses to do so. The first serious negative TV foray on the Democratic side in Iowa and New Hampshire came from a union, the American Federation of State, County, and Municipal Employees, which spent about $340,000 on ads challenging Mr. Obama’s health care plan.

However, the ad campaign prompted an internal fight at Afscme after locals supporting Mr. Obama strenuously objected.

This week, after a report in the Huffington Post that the union and others were considering creating a new group to target Mr. Obama, Afscme’s president, Gerald McEntee, issued a denial. “Afscme is not about the business of swift-boating any Democratic candidate. We will not be party to any effort of this type. Our campaign is about promoting Hillary Clinton — not tearing down any other candidate,” Mr. McEntee said. His statement did not address the previous ads going after Mr. Obama.

The issue is complex because, by law, officials who talk regularly with the candidates and their aides are not permitted to be involved in the union’s independent expenditure efforts. Officials at Afscme’s headquarters said they could not clarify what impact the statement would have on the semi-autonomous operation.

Meanwhile, a group that ran $1.6 million worth of radio and TV ads in Iowa supporting John Edwards, the Alliance for a New America, plans to sit out Nevada and South Carolina, a source involved with the group said.

A spokeswoman for Mr. Obama, Jennifer Psaki, said his campaign is advertising at the moment in Nevada. One spot promotes Mr. Obama’s health care plan. The other includes clips of a widely praised speech he gave in Iowa in December. Mrs. Clinton’s campaign did not respond to an inquiry about its ads.

Of course, Mrs. Clinton and Mr. Obama have many ways doubts about each other without resorting to paid TV spots. “In Iowa, nobody wants to go negative on television, so really it’s a war underneath the radar screen, and it has more to do with how the press interprets it than anything else,” one of Mrs. Clinton’s top strategists, President Clinton, told Charlie Rose on PBS last month.

In New Hampshire, Mr. Clinton complained about flyers and opposition research that he said Mr. Obama’s campaign was circulating. The former president then blasted Mr. Obama for allegedly waffling on the Iraq War.

Mr. Obama’s allies called attention yesterday to an interview in which one of Mrs. Clinton’s backers, Attorney General Cuomo, said a benefit of New Hampshire and Iowa is that candidates can’t “shuck and jive” to avoid hard questions. Mr. Cuomo’s office said the comment was a general observation directed at both Mr. Obama and Mrs. Clinton.

Mrs. Clinton also faces the possibility of an onslaught of negative ads from conservative groups who have long held her in disdain. Three federal judges in Washington held a hearing yesterday on a request by a conservative group, Citizens United, that it not be required to disclose donors backing television ads for a film critical of Mrs. Clinton, “Hillary: The Movie.”

Under federal law, broadcast and cable ads that mention a federal candidate and are aired during certain periods before elections have to be reported to the Federal Election Commission along with the sources of funds for such ads.

Three judges who heard the case expressed skepticism about claims that the film is just a discussion of issues and not a veiled political attack.

“Once you say, ‘Hillary Clinton is a European Socialist,’ aren’t you saying vote against her?” Judge Royce Lamberth asked, according to the Associated Press. When a lawyer for the group, James Bopp, said the film was not related to her presidential campaign, the judge indicated he viewed that as ridiculous. The judges did not rule immediately on the request for an injunction against the disclosure rules.