Jerusalem ? Israel’s opposition Labor Party declared Tuesday it wouldn’t join a government headed by Ariel Sharon — a move that further complicates the messy political scene and makes it highly unlikely any party can form a stable coalition following Jan. 28 elections.

“We will not be in a government led by Sharon. Period,” Labor leader Amram Mitzna said at party headquarters in Tel Aviv, flanked by almost all of Labor’s 26 parliament members. “It’s us or him. Anyone who doesn’t vote Labor is voting for Sharon.”

Sharon’s hawkish Likud party is favored to win the largest number of seats, with the left-leaning Labor Party coming in second, according to polls. However, no party will even approach an outright majority in the 120-seat parliament, and the next government will again be a coalition of several parties.

Likud and Labor were partners in the coalition that collapsed in November, and Sharon, the current prime minister, would like them to again join forces.

If Sharon’s party wins the election but can’t persuade Labor to join the government, it would face difficulties in forming a coalition. Sharon could seek a grouping of several small extreme-right and religious parties, but that would likely produce a narrow and unstable coalition.

The negotiations could easily stretch out for weeks after the election — and if no coalition forms, Israel could face yet another election.

With 15 or more parties likely to win seats in parliament, no single party is capable of getting a majority, leading to unwieldy coalitions. No Israeli government has served out its full term since 1988, and the Jan. 28 ballot will be the fourth national election in less than seven years.