Portugal's conservative coalition today geared itself to face almost certain early elections as the resignation of a third prominent leader within two weeks cast doubt on the coalition's ability to form a new government.

Christian Democrat Basilio Horta, who served as minister for agriculture and commerce in the outgoing government, resigned as vice president and acting chief of his party in opposition to attempts to unite the coalition around a new government led by former education minister Vitor Crespo, who had been proposed by outgoing prime minister Francisco Pinto Balsemao.

Horta resigned after his party voted by a narrow majority to offer limited support to a Cabinet led by Crespo. Horta argued that it was better to face elections now than to join a weak, patched-up government threatened with collapse in a few months.

Thursday, party president Diogo Freitas do Amaral, the deputy premier and defense minister in Balsemao's government, resigned in opposition to Crespo's nomination.

The right-of-center coalition, called the Democratic Alliance, has been trying to agree on a new executive since Balsemao quit as prime minister Dec. 19 after an election setback and criticism of his low-key leadership by hard-liners within his party.

Left-leaning President Antonio Ramalho Eanes has warned that he will dissolve the parliament and call early general elections if the coalition cannot put together a new government strong enough to last the remaining two years of its mandate.

According to one unconfirmed report, Eanes privately has set a Jan. 15 deadline for Crespo to unite the coalition behind him and come forward with solid proposals for a new Cabinet.

Balsemao, empowered by the Social Democratic Party to name his own successor, chose Crespo, 51, after two other candidates turned down the post out of fear that they could not muster sufficient support within the coalition.

Crespo's nomination has sparked little enthusiasm among Social Democrats, and several prominent members of the present government have made it clear they will not serve in any Cabinet he would form.

A chemistry professor trained at the University of California at Berkeley, Crespo was widely criticized during his short term as education minister last year and left the Cabinet in August.

If Eanes calls early elections, the coalition partners have said, they will end their alliance and run on separate election tickets. The chief benefactors of such a development would be the opposition Socialists, who advocate formation of a centrist government in alliance with the Social Democrats.