The Carter administration has tentatively decided that Metro rail construction should be part of the total national transit package and not a separately authorized program, administration sources said yesterday.

That thinking, plus virulent administration opposition to giving Metro special aid to defray its operating deficits, led to Monday's last-minute attack in the House on a $1.7 billion Metro funding bill.

The White House position may not be a final one, several sources emphasized. One called the bill premature, and another said, "I would not want to characterize the hardness of our position."

If the White House takes a hard-line approach that includes a veto threat, a Metro funding bill would be difficult to pass. That, in turn, would put new strains on the already-fragile local Metro political coalition that has held together through years of financial uncertainty.

The bill passed the House by more than 2 to 1 despite the administration's efforts, which were led by the Office of Management and Budget. It is unclear what will happen in the Senate, "but this (the administration's position) definitely will slow us down," one source said. "We're going to have to find out exactly where the administration is and see what can be worked out."

A key White House official said yesterday that "our basic argument was not that we had problems with continuing to fund Metro but that Metro should be part of an overall urban transit investment.

What surprised sponsors of the House bill was the 11th-hour nature of the White House attack.

The administration had testified in hearings last February that it did not favor the bill, cosponsored by Reps. Hebert E. Harris (D-Va.) and Fortney H. (Pete) Stark Jr. (D-Calif.).

However, administration witnesses did not oppose the bill either, and that was where the matter rested until Monday morning.

"I don't think our position should have surprised anybody," the White House official said.

Harris met late yesterday with White House and Office of Management and Budget officials, and they agreed to schedule another meeting on Metro within two days. "We think it's possible to work out the differences," Harris said.

As part of his new energy package, President Carter has outlined a $10 billion mass transit program. That program, to be financed with income from the windfall profits tax on oil producers, would be in addition to the existing national transit program, presently budgeted at about $1.3 billion per year.

One major selling point for proponents of the Harris-Stack bill was that national transit needs would be great in the future and that other cities with heavy needs would have a better chance of getting federal transit aid if Washington Metro was handled separately. Metro was orginally started in 1969 as a separate local-federal project. Only recently has Metro had to compete with other transit programs for available funds.

Major expansion of existing systems or construction of new ones are planned or under way in New York, Boston, Chicago, Miami, Atlanta, Buffalo and Baltimore. Additionally, Los Angeles, Detroit and Honolulu all have ambitious transit plans that would require heavy capital investment and heavy doses of federal aid.

Department of Transportation insiders, especially those in the Urban Mass Transportation Administration, are known to share the view that Metro should be a separate program. Transportation Secretary Adams, however, never supported the Harris-Stark bill, but neither did he openly oppose it.

The White House made clear Monday and yesterday that opposition to Harris-Stack did not influence Adams' decision last week to release $1.2 billion in Metro construction funds over the next three years. The Harris-Stark bill would provide funds for construction after that period.

Included in the bill was a proposal to aid Metro with $197.7 million in operating subsidies over several years. That proposal is opposed throughout the administration - in the Department of Transportation, at the White House and at the Office of Management and Budget.

The argument for special operating assistance has been that Metro serves many federal office buildings and tourist attractions and these should receive extra federal aid. But an administration official countered yesterday by saying that "maybe Metro should give us extra credit for letting them put a station at the Pentagon. That has added a lot of riders and revenue to their system."