Republican National Chairman Bill Brock denounced President Carter's anti-inflation message as "blantantly political" and "too little, too late" yesterday in a statement issued hours before the president's message was delivered.

But Carter's program drew at least some GOP backing as Sen. Jacob K. Javits (R.N.Y.), emerging from a White House briefing for congressional leaders, predicted that it would get "considerable Republican support . . . because it recognizes the program and its endeavoring to cope with it."

Democratic leaders predictably gave the plan their support, although House Speaker Thomas P. (Tip) O'Neill Jr. (D.Mass.) was less than enthusiastic about it.

"I gave my word that I will support his plan," said O'Neill, but he declined to say whether he agreed with the president's prescription for voluntary wage-price guidelines.

Business and labor leaders took a wait-and-see position, although both had voiced skepticism earlier about whether the program would succeed in slowing the rate of wage and price increases. Some also said they feared it would be the first step toward congressional enactment of compulsory wage and price controls.

Labor Secretary Ray Marshall told reporters in a briefing on the plan that he expected a "diverse" response from organized labor, though earlier signs were that the union reaction would be cool if not hostile.

A well-placed union source said earlier this week that unions felt the plan as it was emerging was "unworkable and unfair," and said yesterday after further briefings that nothing new had developed to change that assessment.

"We expect and hope that (the unions will say, 'Let's give it a chance to work,'" Marshall said.

Brock's preemptive strike against the president's plan - which appeared to signal a prominent role for the inflation policy in the final two weeks before the Nov. 7 elections - was coupled with a GOP request for equal time from the networks for a minority party response.

Senate Minority Leader Howard H. Baker Jr. (R-Tenn.) and House Minority Leader John J. Rhodes (R-Ariz.) joined Brock in a telegram to the networks' news divisions asking equal time "in the interests of fair play."

In his criticism, which aides said was based on news accounts of what the president's message was likely to say, Brock said Carter's plan is "rightly being castigated by labor, business and consumer leaders for what is is: too little, too late and too much like the previous three failures."

Brock said inflation has doubled from 5 percent to nearly 10 percent since the Ford administration left office, and accused Carter of placing inadequate focus on government spending and taxation as a cause of inflation.

Rep. Robert N. Giaimo (D-Conn.), chairman of the House Budget Committee, called the program "a very real step to get things under control."

Rep. Philip M. Crane (R-III.), a candidate for the Republican presidential nomination in 1980, said Carter was engaging in a "shell game" that will lead to "arbitrary dislocations in the economy."

Meanwhile, an ABC News-Harris Survey released yesterday showed that, while those polled favored wage-price guidelines by 73 to 19 percent, they also said they didn't think such a plan would work.

The poll also showed an increasingly large margin of support for mandatory wage-price controls: 58 to 35 percent for controls this month, as opposed to 52 to 42 percent for controls last month.