Several Democratic members of Congress yesterday welcomed the call by some Roman Catholic bishops for increased spending on the poor but questioned whether it is realistic in the current conservative political climate.

"It will be interesting to see whether the bishops' statement spurs the conscience of American public policy-makers," said Rep. William H. Gray III (D-Pa.), vice chairman of the Congressional Black Caucus. "It may be a catalyst to make those who acted as if poverty did not exist reexamine that question."

Gray, a Baptist preacher, also said the $180 billion federal budget deficit "almost eliminates any possibiity for new programs to attack rising poverty, structural unemployment, or education or health care. The question of massive federal spending is a moot point."

The National Conference of Catholic Bishops yesterday began what is expected to be a yearlong debate on the proposed pastoral letter, which says the United States has an obligation to deal with the "moral and social scandal" of widespread poverty and unemployment.

Among other things, the broadly worded letter calls for federal programs to reduce unemployment to between 3 and 4 percent, increased welfare benefits, a reduced tax burden on the poor and attempts to improve educational, child care and job opportunities for minorities.

But some members of Congress who could be reached on the Veterans Day holiday questioned why the letter was withheld until the presidential campaign was over. The bishops said this was done to keep the issue from becoming politicized.

"It's coming out when the game is over and the fans have left the field and a few beer cans are still lying around," said Sen. William Proxmire (D-Wis.). Politics, he said, "is the name of the game. There's no other way to do things in this country than to get a president and Congress that support these goals. Maybe they think they can do it through an act of faith."

There was widespread agreement yesterday that the bishops' message will have major political significance.

"The debate about the poor in this country could have come to a crashing halt after Nov. 6," said Rep. Timothy E. Wirth (D-Colo.). "The bishops have kept it open, and I think that's great."

The dialogue sparked by the proposed pastoral letter appears to coincide with the emerging debate about the direction of the Democratic Party following President Reagan's 49-state victory over Walter F. Mondale. Although Mondale refrained from urging major new spending programs, many interpreted the election results as a repudiation of New Deal-style liberalism.

"In Reagan's America, poverty does not exist," Gray said. "Inequity and injustice are nonexistent. In the campaign the Democrats were talking about poverty and injustice -- reality -- and the administration was talking about hope and what we would like ourselves to be.

"What Nov. 6 said is that people . . . did not want to face these problems," Gray said.

Wirth, one of the younger Democrats concerned about the growth of the economy, said the party faces a difficult dilemma.

"The Democratic Party has a challenge for doing two things -- to recommit itself to the concept of economic growth and to maintain its commitment to individual opportunity," Wirth said. "Sometimes those things appear to be mutually exclusive. Good politics is figuring out how to reconcile the two."

Proxmire, a frequent critic of certain forms of federal spending, said it would be "very, very hard" for Congress to fashion a politically acceptable antipoverty program.

"There's a feeling on the part of some people that the welfare system isn't working, that it's abused, that people are trying to get handouts," Proxmire said. "You have to get programs that work much better than CETA the defunct federal jobs program and require states to pick up more of the tab. You can't train people for jobs that don't exist."

Gray said he thinks that a 4 percent jobless rate is a realistic goal.

"There are areas of the country -- I'm from one -- that have not really felt the effects of the recovery," the Philadelphia congressman said. "Black unemployment is higher today than it was in 1981." But he said any large-scale employment program is unlikely.

Gray also questioned the timing of the letter, noting that the bishops did not hesitate to inject their antiabortion views into the campaign.

"Why have we never heard this brought before the American public prior to Nov. 6, when it could have had a tremendous impact in increasing the debate on these issues?" he asked. "Certain other questions were raised that were perceived as being political, so why not raise this one?"