The Rev. Robert J. Cornell, acknowledging "surprise and disappointment," yesterday became the second U.S. Roman Catholic priest to abandon political life at the behest of Pope John Paul II.

Cornell, a Wisconsin Democrat, served two House terms before being defeated in 1978. He was seeking election in state's 8th Congressional District. Yesterday Cornell said he was scrapping his two-week-old race because of a papal decree barring priests from secular politics.

"I would be less than forthright if I did not acknowledge my surprise and disappointment at the recent decree of Pope John Paul II regarding priests seeking public office," Cornell said at a news conference in De Pere, Wis.

The priest said he did not find the religious life incompatible with his life as a politician. He said his four years in Congress "were the most fulfilling in my life."

However, Cornell said he is unwilling to abandon the priesthood to pursue a political career. And even had he chosen that path, it would not have led him back to the House from his heavily Catholic district, Cornell said.

"I am realistic enough to recognize that . . . if I chose to run under these circumstances, there would be little chance of a successful campaign. I am, therefore, withdrawing my candidacy for the 8th congressional seat," Cornell said in the presence of some tearful campaign supporters.

On the House floor in Washington yesterday, the scene was a little different. There, Rep. Robert F. Drinan (D-Mass.), the Jesuit priest-congressman who announced Monday that he would not seek reelection because of the papal order, was warmly greeted by many of his colleagues. Many lawmakers shook Drinan's hand and patted him on the back.

House Speaker Thomas P. (Tip) O'Neill Jr. (d-Mass.) praised Drinan's 10 years of service in the House. Later, O'Neill told reporters he was sorry Drinan was stepping down at the end of his term. "But it's a dictate of the church," he said.

That "dictate of the church" was still the subject of much clerical confusion yesterday. But at least, according to church officials interviewed by The Washington Post, the order to Cornell to drop out of politics, and his obedience, made some things clear.

Drinan, a liberal who, among other things, supported federal abortion aid, was not being singled out by the Vatican, as one news organization reported.

Nor were the Jesuits being singled out, the Catholic official said. Cornell, they pointed out, is a member of the Norbertine Order.

"This is an application of general church law," said a spokesman for the Most Rev. Jean Jadot, the apostolic delegate and Pope John Paul II's representative in Washington.

"It is clear that it's not Drinan, as an individual, who is being cited.

"The pope has spoken very clearly on this matter," the spokesman said, in a reference to clerical involvement in politics.

"This pope is saying the whole purpose of the church is to spread the gospel -- that is the proper work of the priests and nuns.

"The role of the laity is the temporal order -- politics, social action and what have you. . . . The pope is making it clear that the ordained clergy has one role and the laity has another," the spokesman said.

However, Jadot's spokesman said that nuns serving in elective office are technically correct when they say the no-politics order does not apply to them, because they are not considered members of the ordained clergy.

"The church law, canon law, does not apply to nuns in the strictest sense," he said. "But the spirit of the law is another matter."

He added that the pope primarily is concerned about priests engaging in partisan politics, and about Catholic religious who are involving themselves in social and political causes, whether those causes are of a conservative or a liberal nature.

Strictly speaking, "the application of the general church law" on clerics and secular politics does not apply to priests holding nonelective, policy-making positions, the spokesman said.

However, he avoided direct comment on the Rev. Geno Baroni, a diocesan priest and liberal activist who currently serves as an assistant secretary in the Department of Housing and Urban Development.

The spokesman, commenting cautiously on the Vatican's new push to implement church laws on clerical political involvement, said: "They're speaking about elected public officials."

Cornell, 60, was told by his bishop, the Rev. Aloysius Wycislo of the Catholic diocese of Greeen Bay, Wis., not to run for office. Wycislo was acting on orders from the pope's Washington delegate, Jadot. Jadot's spokesman said Jadot was acting on the orders of the pope.