William D. Ruckelshaus vowed yesterday to use all the tools at his disposal to enforce the nation's environmental laws, telling a Senate panel that there would be "no hit lists, no . . . political decisions and no sweetheart deals" with him as administrator of the Environmental Protection Agency.

But he declined to commit himself to seeking a bigger budget and more personnel for the agency, which administration critics have called the first and most important step to restoring the EPA's effectiveness.

In his first day of testimony before the Senate Environment and Public Works Committee, which is considering his nomination to replace Anne M. Burford, Ruckelshaus assured senators that he would have President Reagan's personal support in his efforts to put the agency back on track.

Burford's lack of access to the White House and her perceived subservience to Interior Secretary James G. Watt on environmental policy have been cited as major elements in the controversy that has impaired the agency over the last two years.

Ruckelshaus said White House aides have assured him that "within any 24-hour period, if I make a strong plea to see the president, they'll get me in to see him." He also said he did not anticipate any conflict with Watt, who chairs the Cabinet Council on the Environment.

"There will be no interference by me in what his responsibilities are, and none by him in what mine are," Ruckelshaus said, adding that he had been assured that he will have a Cabinet council seat, which had been denied Burford.

But Sen. John H. Chafee (R-R.I.) reminded Ruckelshaus that Burford, at her confirmation hearings two years ago this week, had said much the same thing. "I was assured that her voice alone would be the voice of the environment," he said. "Although she may have thought that was true at the time, nothing could be further from the truth."

In his formal statement to the committee Ruckelshaus said Reagan agreed with him that "people and resources to do the job were essential ingredients of success."

But, under questioning, he declined to pledge his support for increasing the agency's budget, which has been cut by 30 percent in the last two years, "until I have a chance to review the policies and program needs in more detail."

Despite occasionally sharp questions from Republican and Democratic members, the panel's approval of Ruckelshaus, who served as the EPA's first administrator from 1970 to 1973, appeared to be a foregone conclusion.

In more than an hour of opening statements, including a visit from Senate Majority Leader Howard H. Baker Jr. (R-Tenn.), Ruckelshaus was praised as a man of integrity, intelligence and devotion to duty.

But Chairman Robert T. Stafford (R-Vt.), who also praised Ruckelshaus' record of service, said he wanted "to determine how much the nominee has changed his views over the intervening years" while he has been an executive for the Weyerhaeuser Co., a forest products firm.

Referring to letters obtained by the committee in which Ruckelshaus, as a Weyerhaeuser executive, attacked the Clean Air Act and other environmental laws, Stafford asked, "Will he enforce not only the letter of those laws with which he may disagree, but the spirit of them as well?"

In his formal statement, Ruckelshaus said he would. "Let me disabuse anyone who believes EPA, while I am there, will not have the requisite determination to enforce the laws as written by Congress," he said.

He said he had written the letters as part of the "national dialogue" on environmental issues, and "if confirmed you will hear me making many of the same arguments I have made in the past, whether in or out of government."