ANNAPOLIS, DEC. 1 -- A newly confident Maryland Republican Party reveled one more time in its good fortune at the polls this year, then turned its attention today to the 1992 elections for U.S. Senate and House seats.

"We became a two-party state last month, and we're not going to turn back now," said Joyce L. Terhes, who was reelected state GOP chairwoman as the party ended its convention here.

The Republican Party surprised the long-dominant Maryland Democrats Nov. 6 by winning county executive races in Anne Arundel, Howard and Baltimore counties and picking up the 1st District seat in the House of Representatives, giving it control of three of eight House seats from the Free State. The GOP also gained 11 seats in the General Assembly, bringing its total to 34 out of a total of 188 members.

"This year, we're all in the Christmas spirit," said Baltimore County Republican Chairman Richard D. Bennett, who is soon to become U.S. attorney for Maryland.

Although the Republican Party still lags behind Democrats by a ratio of almost 2 to 1 in Maryland voter registration and does not hold a statewide office, leaders said during meetings today that it can build easily on the 1990 record of success at the polls.

A measure of the party's new stature was the rapid emergence of potential candidates willing to take on Sen. Barbara A. Mikulski (D-Md.), who comes up for reelection in 1992. Said one party leader, "A number of them feel that now that Maryland is a two-party state, they're interested in doing it."

Among those circulating through the crowd at the convention today was Joseph E. diGenova, former U.S. attorney for the District of Columbia. DiGenova acknowledged that he has interest in the Senate race, but said he was "merely consulting, meeting people, testing the waters."

"The gains this year have strengthened the party's confidence about what it's capable of doing," diGenova said in an interview.

Also reportedly considering seeking the Senate seat are former ambassador Alan L. Keyes, the GOP nominee defeated by Sen. Paul S. Sarbanes (D-Md.) in the 1988 Senate race; novelist Tom Clancy; unsuccessful state comptroller candidate Larry Epstein; and Rep. Helen Delich Bentley (R-Md.).

Bentley, the party's national committeewoman, shrugged off suggestions that she might opt for a Senate campaign in two years. "I haven't made a decision on anything," said Bentley, whose House district covers parts of Baltimore and Harford counties.

In a keynote luncheon speech, Bentley said the GOP took advantage of Democratic arrogance this year, and was positioned with good candidates at election time. "Now we need to broaden our base and take more seats in the next election," Bentley said. "I look forward to 1992, when we pick up another House seat or two and pick up the Senate seat."

Terhes, who took over a largely divided party a year ago and brought it out of debt, was reelected party chairwoman after her lone challenger, Calvert County Commissioner Mark Frazer, withdrew.