A conservative House Republican said yesterday that President Reagan and his aides are "deluding themselves" if they think the controversy over Interior Secretary James G. Watt is "behind us." He asked the president to fire Watt to prevent political damage.

Rep. Newt Gingrich (R-Ga.) told a news conference that "Watt's sick joke is a slur on millions of Americans," and said the furor over Watt's remark "is incredibly destructive for the Republican Party and its president," and will not subside.

Gingrich's statement reflected continued pressure among Republicans on Capitol Hill for Watt to resign for describing an advisory panel as "a black , . . . a woman, two Jews and a cripple."

At the same time, the White House reaffirmed that Reagan will not press Watt to step down for the remark, a stance that has strengthened the secretary's belief that he can ride out the furor, administration officials said. No-confidence resolutions against Watt are pending in the House and Senate.

At Interior, the official news summary distributed daily to employes yesterday contained no articles reporting pressures on Watt to step down.

Instead, it included eight reports of support for Watt in the face of the controversy, including an article headlined "Watt will be staying, White House affirms" (Washington Times); an editorial, "Defense of Mr. Watt" (Anchorage Times); a wire service report about a pro-Watt campaign by a large Christian television network, and the text of a Paul Harvey broadcast on the matter.

Meanwhile, Senate leaders said they will probably block the no-confidence resolution from coming to a vote, removing a major threat to Watt's future. A no-confidence vote by the GOP-controlled Senate would seal Watt's fate, White House officials said.

At least 13 GOP senators have either called for Watt's ouster since the remark or questioned his effectiveness. A private survey by Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) reportedly indicated the resolution would pass easily, with significant GOP support.

At the same time yesterday, National Park Service Director Russell E. Dickenson said that a headline in yesterday's Washington Post was "grossly misleading" in saying: "Interior to Expand Mining in Parks."

The Post reported yesterday that the new regulation, to take effect Oct. 14, expands the rights of mining companies to coal deposits under 3.7 million acres of private land within national parks. Dickenson was quoted in the article as saying the park service will move quickly to buy or condemn land in the parks if private interests establish mining rights under the new rule.

"National Park Service policies prohibit the mining of coal in areas of the National Park System," Dickenson said yesterday. The new strip regulation provides "significant protection to park resources," he said.