President Reagan complained yesterday that House Democrats are trying to sidetrack for months his proposed $100 million package of aid for Nicaraguan rebels and warned that such delays could result in defeat of the rebels and "a verdict of shame on us all" in the history books.

In a speech on the eve of showdown House votes this week, Reagan criticized House Democratic leaders' plans to link the aid to a new spending bill that he said could result in "a forest of legislative delays."

Speaking to the Associated General Contractors, Reagan warned against "subterfuge and backroom deals" that he said would "damage this nation's foreign policy" and said "the lives of countless young Nicaraguans will be put in jeopardy."

His comments were directed at the House Democratic leadership decision to include such aid in a $1.7 billion supplemental appropriations bill that Reagan has vowed to veto.

The bill includes such politically sensitive spending as disaster relief and aid to Northern Ireland and would also cancel Reagan's budget deferrals and his power to defer spending approved by Congress.

White House officials said Reagan would seek a defense on the House floor of his aid package, which has $70 million in military assistance and $30 million in nonlethal aid. While officials said Democrats have indicated that they do not want to defeat Reagan on a "parliamentary trick," there was no sign that Democrats would separate the proposal from the money bill.

"If the House votes yes, but aid doesn't go through -- or if the House amends our bill to block the defensive weapons the freedom fighters need -- there is no question that the lives of countless young Nicaraguans will be put in jeopardy," Reagan said.

An aide to House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) acknowledged that ground rules for the aid debate are "complicated," but he denied that they are loaded against the administration.

"The rule gives them the possibility of sending a contra aid bill as passed by the Senate back to the Senate," he said. He said this could be done if Republicans win approval of their aid proposal, then defeat the fiscal 1986 supplemental appropriations bill to which it will be attached if both clear the House.

Rep. David E. Bonior (D-Mich.), a member of the House Rules Committee, said committee members were being criticized by some liberal Democrats for even allowing this possibility. He said that, when O'Neill promised that a second vote on contra aid would be held this week in connection with consideration of the appropriations measure, he did not commit himself to any mechanism that would allow separating the two bills.

Congressional Republicans charge that the spending bill is so loaded with "pork" and other provisions of special interest to various lawmakers that it will be virtually impossible to defeat on the House floor and allow a contra aid package to stand on its own.

Meanwhile, congressional jockeying continued before this week's votes.

The House Republican leadership introduced a complex parliamentary resolution aimed at forcing a third series of votes on the contra aid issue in mid-May. They described this as a "fall-back" position for this week's debate.

The first key vote is scheduled late this afternoon when administration supporters are expected to try to defeat ground rules for the aid debate and substitute their own. The GOP proposal would separate the aid package from consideration of the supplemental appropriation.

On Wednesday, the House is to debate and vote on two different versions of a contra aid package and a liberal Democratic proposal to provide funds to assist Nicaraguan rebels but not the contras.

Meanwhile yesterday, Rep. Michael D. Barnes (D-Md.), a leading opponent of administration policy in Central America, charged that the United States is "careening blindly toward a wider war in Central America."

Based on information supplied to Congress by the State Department, he said, the administration cannot account for how much of the $27 million in nonlethal "humanitarian" aid provided to the contras last year was spent.

He also said the administration violated legal restrictions set by Congress if, as has been reported, the Central Intelligence Agency secretly funneled millions of dollars to the contras for political projects over the last year.

Also yesterday, Rep. Edward J. Markey (D-Mass.) said only $400,000 of the $20 million sent to Honduras was used to repel last month's border incursion by Nicaraguan government forces. Markey asked Reagan not to send more of the money.