Republican National Chairman Bill Brock announced an ambitious plan yesterday to select, train and finance full-time organization directors for all 50 states.

Brock elected earlier this month as new chairman of the GOP, said he would seek $1.7 million for the project in the 1977 budget he is now preparing.

The plan to put a professional organizer into each state is the keystone of what the former Tennessee senator called "a long-term effort to rebuild the eroded base of Republican support around the country."

Brock said the full plan, still under development will include a heavy emphasis on candidate recruitment and communications to voting blocs where Republicans are weak - including blacks, Hispanics, organized labor, ethnic groups, the elderly and young voters.

Referring to public opinion polls showing Republicans now constitue only 18 to 22 per cent of the electorate, Brock said. "We've got to do a lot more than get our 18 per cent together. We can do that perfectly and still lose every election for the next 100 years."

But at the same time, he said, organizational efforts were important because, with Republicans in the White House for 16 of the last 24 years, "we'd become a presidential party and we'd let our base rode."

Both parties in the past have employed field representatives, usually on a regional basis, to assist local candidates and organizations.

But Brock's plan is far more ambitious, not just in cost but in its redefinition of state and national party responsibilities, than anything that has been attempted previously.

"We'll provide each state with an organization director that we will train," he said. "We'll pay them and, to the extent possible, we'll pick them. We'll require that they be retrained up here twice a year to carry out our program."

Later, Brock amended that description slightly, saying that the selection and assignment of the organization directors would be "a matter of negotiations with the states.The state organizations will pay their expenses. They'll work for the state chairman, but they'll be trained by us and report to us."

Brock said that at present Republicans have "professional organization people" in only half the states. He said the first priority for the new corps of organizers would be preparations for legislative elections in 1978.

In other comments to a breakfast group of reporter, the new GOP chairman said President Carter's inaugural speech strengthened his belief that Carter "will try to be a fairly conservative President, staying in the broad middle stream."

Brock added that if Carter pursues that course, he will quickly find himself in conflict with the heavily Democratic Congress, which Brock said "is way to the left of the country."

"It will be very difficult for him (Carter) to hold them (the members of Congress) down," Brock said. "There will be tensions within Congress, between Congress and the President and between the President and the disparate elements of the Democratic Party."