Gov. Michael S. Dukakis yesterday compared George Bush's campaign to the Watergate scandal of Richard Nixon, saying "truth was the first casualty" in both instances. Bush received new police endorsements along with the badge of a slain officer in New York.

The Democratic governor and the Republican vice president dueled from a distance on the campaign trail before sheathing their political swords and dining together at the annual, nonpartisan Alfred E. Smith charity dinner in Manhattan, sponsored by the Roman Catholic archdiocese of New York.

Dukakis, urged by supporters to get tough in the face of polls that show him trailing Bush, did just that during an appearance in New Haven, Conn.

"Truth was the first casualty in the Nixon White House and it was the first casualty in the Bush campaign," Dukakis said. "Above all, the truth should matter a lot in a presidential campaign because as we learned in Watergate, it matters a lot in the Oval Office."

"I believe the American people value the truth in politics, and I'm going to do everything I can to make sure truth wins and that we win on the eighth of November," the Democratic nominee said.

Dukakis also made a point of drawing a distinction with Bush on the emotionally charged subject of abortion.

"George Bush wants the government to make one of the most personal choices a woman can make....I believe a choice that personal must be made by the woman herself."

In almost every speech he makes, Bush says he opposes almost all abortions while Dukakis does not.

Dukakis was greeted by news of a poll saying he is 10 points behind Bush in Connecticut, a state that borders his home base of Massachusetts. "You know the polls," Dukakis commented. "They go up and down."

Bush, campaigning in a state once considered a stronghold for Dukakis, traveled to the New York City borough of Queens to receive police endorsements and to campaign in a Democratic neighborhood.

Along with the badge of slain officer Edward Byrne came the endorsement of about 30 police organizations, including the 40,000-member Police Benevolent Association of New York.

"It's time for America to take back the streets," Bush said, calling the new police backing "an exclamation point" for his campaign. Both he and Dukakis have made much of endorsements from law-enforcement organizations during a campaign in which Bush has sought to portray Dukakis as soft on crime.

The vice president spoke at a high school in Queens, not far from where officer Byrne was shot last February in his car while guarding a witness in a drug case.

The slain officer's father, Matthew Byrne, a retired New York police lieutenant, said he was giving Bush his son's shield and commendation bar "because we believe he and his administration will stand up for us."

Rich Bond, Bush's political director, contended that Dukakis' political base is cracking. Bond called New York "the jewel in his base, and it's shaky for him."