The Democratic-controlled House will be responsible for "a national-security disaster" if it fails to provide $100 million in aid to embattled anti-Sandinista rebels in Nicaragua, President Reagan said yesterday.

Speaking to Republican officials and candidates, Reagan renewed his drive for the aid by saying that the leftist Sandinista government is trying to wipe out the rebels while Congress dawdles on the aid request.

"The strategy of the Sandinistas should now be clear to everyone," Reagan said. "It's a strategy of delay, dragging out negotiations, never taking a serious position so they can wipe out the opposition while Congress waits to see if a peace treaty is around the corner. Well, if we continue to delay, all we're doing is playing into the hands of the Nicaraguan communists."

A senior White House official said the administration is six to 12 votes short of a House majority on the aid request but thinks that it will be approved in some form if House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) allows a second vote on the previously rejected package.

Earlier in the day, White House spokesman Larry Speakes criticized O'Neill for postponing the promised second vote "that we thought had been assured for this week."

Speakes said the situation is "critical with the democratic resistance forces," which he described as living a meager existence while the Sandinista forces try to "drive them into the ground."

The $27 million in nonlethal assistance approved last year by Congress for the counterrevolutionaries, known as contras, runs out at the end of July. The administration is seeking an additional $70 million in military aid and $30 million for food and supplies.

Reagan, in an emotional speech kicking off an intensive campaign to prod the House into voting on the issue, said denying the aid "is a mandate for inaction which could well result in the creation of another Libya on our doorstep" that would menace the United States and Nicaragua's neighbors.

"If the opponents of aid have their way, preventing us from assisting our friends, Central America could soon become a divided, war-torn region, with Nicaragua a refuge and safe haven for terrorism," Reagan said. "If this happens, the American people will know who to blame."

The president stopped short of specifically blaming the Democrats as a party. White House officials are anxious to avoid repetition of what some of them consider an excess of partisanship in the campaign for contra aid last March.

In a Washington Post article March 5, White House communications director Patrick J. Buchanan said that "with the vote on contra aid, the Democratic Party will reveal whether it stands with Ronald Reagan and resistance -- or Nicaraguan President Daniel Ortega and the communists." The article particularly angered Democrats who had supported previous contra-aid requests.

While the administration is casting the aid proposal as a bipartisan national-security issue, Reagan's remarks to a Republican audience suggested that he is ready to make it a partisan cause if the House again rejects the request.

"Deserting the Nicaraguan freedom fighters would be a national- security disaster for the United States," Reagan said. "And together we can see that this never happens."

The House turned down the aid package March 20 by 12 votes, but the Senate approved it a week later by six votes. O'Neill has promised another vote, but the timetable has slipped. White House officials say the vote may not come before June 23