WARSAW - Poland`s polling stations opened at 6:00 am (0400 GMT) Sunday in a snap election forced by the air-crash death of conservative president Lech Kaczynski.

Acting head of state Bronislaw Komorowski, the governing liberals` candidate, faces the late president`s identical twin, conservative opposition leader and ex-prime minister Jaroslaw Kaczynski.

Polling stations in the nation of 38 million close at 8:00 pm (1800 GMT). Official results are due Monday.

Lech Kaczynski perished on April 10 when his jet crashed in Smolensk, western Russia as it landed for a World War II commemoration. A total of 96 people died, among them his wife, senior politicians and the Polish military`s top brass.

Under the constitution, speaker of parliament Komorowski became acting president after the crash.

He had in any case been poised to stand against Lech Kaczynski in an autumn election and was tipped to foil his bid for a second five-year term.

Komorowski topped a June 20 first round with 41.5 percent of the vote, short of the 50 percent needed to win outright. Kaczynski scored 36.5 percent, setting up Sunday`s run-off.

Both men have courted the electorate of left-winger Grzegorz Napieralski, third two weeks ago with an unexpectedly-high 13.7 percent.

Seven other candidates from across the political spectrum scored less than two percent in the first round.

Most of Napieralski`s electorate is expected to swing behind Komorowski.

But a flurry of final surveys suggested the race could still be tight, with floating voters holding the key.

A range of polls gave Komorowski 45-54 percent support, and Kaczynski, 42-45 percent.

BDST: 12:57 HRS, July 4, 2010