The fight over what to do with the $2 billion saved by President Carter's veto of the Nimitz nuclear aircraft carrier started yesterday as the Pentagon sent Congress a wish list of other projects that would use up every cent.

"It is essential to our security," said Defense Secretary Harold Brown in a letter to Chairman Melvin Price (D-Ill.) of the House Armed Services Committee, to push the total Pentagon budget back up to the $126 billion the president has recommended for parent effort to counter charges that Carter's veto of the carrier showed he the coming fiscal year.

Brown's letter, together with his four-page list of military projects to be financed by the $2 billion, is an apnational defense.

Rep. Jack Kemp, a New York Republican considering a presidential bid in 1980, was among those lawmakers who made that charge during last week's unsuccessful House attempt to override the veto of the fiscal 1979 defense authorization bill.

Hawkish committee members are prepared to assail that veto anew today when Brown testifies on what changes he would like to see in the defense bill other than deletion of the Nimitz carrier.

"Neither the Defense Department nor, I believe, your committee," Brown wrote Price, "seeks a defense program for fiscal year 1979 smaller in constant dollars than that enacted for fiscal year 1978, as would probably result from a simple deletion" of Nimitz money.

"We all share the desire to provide the United States with a strong defense," Brown wrote.

In an interview yesterday Price said it is his intention as chairman to make as few changes as possible in the vetoed bill, after deleting the carrier, so the measure can clear his committee as early as next week. But he conceded that other committee members may try to rewrite the whole bill.

One other major change Price is recommending to his colleagues is to give $209 million to the Navy so it can start paying off disputed bills filed by the Electric Boat Division of General Dynamics and the Newport News shipbuilding subsidiary of Tenneco.

Rep. Thomas J. Downey (D-N.Y.) has introduced a resolution to prohibit those payments to shipbuilders on the ground it is an unjustified "bailout" at taxpayers' expense. Sen. William Proxmire (D-Wis.) is making a similar attempt in the Senate. But unless either chamber passes a disapproval resolution by Tuesday, an unlikely prospect, the Navy can pay off those claims under expedited procedures.

Price and his allies on the committee are not inclined to go along with Brown's wish list for using the Nimitz money because it would require rewriting the whole bill at a time when Congress is rushing to adjourn.

In all, Brown listed $2.225 billion in military projects that he would like Congress to find in the authorization and appropriations bills financing defense activities. Of that total, the House and Senate Armed Services committee would have to authorize $545 million, since they set money to operate the armed forces.

Price led the unsuccessful House effort to override Carter's veto of the $36.9 billion dfense authorization bill. Asked yesterday why he fared so poorly, Price replied: "The telephone." He explained that White House officials conducted an intensive lobbying campaign to get members to back the president.