The bumper stickers plastered onto the utility poles along the main street of Lansdowne, Pa., leave little doubt about the tone of this political year.

"Stop Abortion -- Stop Edgar" the signs implore, a call for the defeat of Democratic Rep. Robert W. Edgar, a Methodist minister who is being painted as an agent of the devil.

Edgar is a prime target of the right-to-life movement, but the nasty battle for his suburban Philadelphia seat is by no means unique.

In race after race across the country, House candidates are being helped -- and hurt -- by intense political armies marching with uncustomary stridence.

In rural Illinois, Rep. Paul Findley, a Republican who thinks the United States ought to be talking to the Palestine Liberation Organization, has become anathema to Jews from across the country, who are funneling great gobs of money to his opponent, a Jew.

Teachers in Indiana, fearful that two of their good Democratic friends, Reps. Floyd Fithian and John Brademas, may be turned to pasture, have mobilized with abandon to get out the vote.

Throughout Alabama, the Moral Majority, the Protestant evangelical group, has mounted a massive campaign to encourage candidates who follow the pro-life, pro-moral, pro-family, pro-America line, as Moral Majority describes it.

The elderly in Portland, Ore., have created a veritable machine to promote the election of Ron Wyden, a young lawyer who has built a career on helping senior citizens.

There's nothing very newsy about special-interest blocs stumping for a favorite candidate. What's new is their intensity in 1980, with the noise and pressure from right-to-life organizations headlining it in many districts.

The case of Rep. Edgar is illustrative. He is a three-term Democrat, the first elected in the district since 1856, who is deemed by conservative groups to be vulnerable this year.

"Baby-killer" was lettered on his car by vandals. Demonstrators appear outside his public meetings carrying posters depicting fetuses in trash cans. Voters are being peppered with copies of Edgar's record on abortion legislation, which is seen as too permissive.

Edgar, who favors some restrictions on abortion, is counting on a backlash and his own polls, which show only 9 percent of voters in his district opposing abortion, to carry him to reelection.

It's another story in the 20th district of Illinois, where Democratic challenger David Robinson of Springfield has raised $346,000, the bulk of it from outside the district, in his race against Findley.

The uproar there concerns Findley's long-standing belief that Yasser Arafat and his Palestine Liberation Organization will not abandon terrorism until the United States begins to deal with them directly as part of its Mideast policy.

A centerpiece of Robinson's campaign was a fund -- raising ad placed in Jewish newspapers in some major cities, with a line describing Findley as "a practicing anti-Semite" and crony of terrorist Arafat.

The money rolled in, but the ad created controversy, among Jews as well as among Findley allies. The "anti-Semite" line was a quote from Jim Klabber, a former St. Louis official of the Anti-Defamation League of B'na B'rith, the Jewish defense organization.

ADL official Dave Brody in Washington termed the ad "beyond the pale" and ADL's Seymour Ardam in Chicago said, "We are quite furious, very upset about the type of campaign Dave Robinson has mounted. Klabber's remark attacks our credibility with many legislators."

According to aides, Robinson next week will publish full-page ads retracting and apologizing for the Klabber remark and is sending letters of apology to contributors he invited to a Washington fund-raiser.

Findley, senior Republican on the House Foreign Affairs Mideast subcommittee, was angered by the Robinson ads. "I believe I have one of the most consistent records on human rights in Congress," he said yesterday. "And I've supported every money bill for Israel over the years in the committee. I did support an amendment rebuking Israel for its settlements policy and I have criticized the bombardments of southern Lebanon. I have been critical of excesses on both sides."

Things are slightly more subtle in Alabama, one of the states where the Rev. Jerry Falwell's fundamentalist Moral Majority is attempting to inspire voters to pick the "right" candidates, although it endorses none by name.

After his surprise defeat in the primary, GOP Rep. John Buchanan, a minister, bitterly denounced the Moral Majority, which he said had distorted issues and ideas in his campaign.

The organization has moved more actively since then, according to state director Stuart Gaines, "to educate, to raise awareness, heighten interest and activity and make people aware of the candidates' records. . . . It lets the candidates know where we stand and where we're coming from."

Senate candidate Jeremiah Denton, a Republican and retired admiral; GOP Rep. William L. Dickinson of Montgomery and Albert L. Smith, who upset Buchanan, have been identified by Moral Majority as supporters of its principles.

"Our people are intelligent. We don't lead them around by the nose," Gaines said. "They understand if a candidate follows our principles. We think this will have a goodly impact on the election."

So these armies march, all to different drummers in a year of jarring cadences. One of the more unusual forces is that put together by Wyden, the Democratic candidate in Portland.

"The seniors are the backbone of our campaign now, as they were in the primary," Wyden said. "Many of them are walking for me. They run the phone banks, they put my signs on their lawns. In Oregon, you win at the doorstep and the seniors understand that."

Wyden came upon this volunteer army through his work in a legal-services program for the elderly, as an unpaid organizer of the Gray Panthers and as orchestrator of a successful statewide campaign in 1977 to allow nondentists to fit and sell false teeth.

Wyden's work provoked the ire of dentists, who sent in thousands of dollars from around the country, but he won the undying gratitude of the seniors. He is heavily favored to win.

Friends are when you need them, and in Indiana it is the teachers who have mobilized to help Fithian and Brademas fend off GOP challengers.

In Brademas' South Bend district, where he is in a close race, the teachers and labor unions have formed a coalition to get out the Democratic vote and return the House majority whip to Washington.

Fithian, a former professor at Purdue University, is counting on energized teachers in Lafayette, in Lake County and the farm communities to help him stay in Congress. They are telephoning, visiting homes and aiming to mail more than 90,000 personal postcards urging his reelection.

In a year when Ronald Reagan is favored to sweep Indiana, few Democrats there feel safe. Fithian, elected in 1974, is the only Democrat to represent his district in this century. On that sort of battleground, he needs an army. h