KISUMU, Kenya, Oct 26 (Reuters) - Kenyan opposition supporters skirmished with police and threw up burning barricades in pockets of the country on Thursday, seeking to derail President Uhuru Kenyattas likely re-election with a low voter turnout.

The election commission said the majority of polls had opened but voting would be delayed until Oct. 28 in four of Kenyas 47 counties - all in the opposition-supporting west - due to security challenges.

The repeat election is being closely watched across East Africa, which relies on Kenya as a trade and logistics hub, and in the West, which considers Nairobi a bulwark against Islamist militancy in Somalia and civil conflict in South Sudan and Burundi.

In the western city of Kisumu, police used tear gas and fired live rounds over the heads of stone-throwing youths heeding opposition leader Raila Odingas call for a voter boycott. Gunfire killed one protester and wounded three, a nurse said.

In Homa Bay county next door, police said they shot dead one protester and injured another.

Riot police fired tear gas in Kibera and Mathare, two volatile Nairobi slums. Protesters set fires and threw stones in Kibera, and in Mathare a church was firebombed.

Around 50 people have been killed, mostly by security forces, since the original Aug. 8 vote. The Supreme Court annulled Kenyattas win in that poll on procedural grounds and ordered fresh elections; but Odinga pulled out of the rerun and urged a boycott because, he said, the poll would not be fair.

In the capital, polling stations saw a sprinkling of voters instead of the hours-long queues that waited in August.

With Kenyatta all but ensured a victory, eyes are on the turnout, which was nearly 80 percent in the August vote.

We are requesting them (voters) humbly that they should turn out in large numbers, Kenyatta, the U.S.-educated son of Kenyas founding father, Jomo Kenyatta, said after voting. Were tired as a country of electioneering and I think its time to move forward.

A decade after 1,200 people were killed over another disputed election, many Kenyans feared violence could spread.

As well as delayed voting, the poll is likely to trigger legal challenges to the result, stirring longer-term instability and ethnic divisions.

On Wednesday, the Supreme Court was due to hear a case seeking to push back the polls. But it was unable to sit after five out of the seven judges failed to show up.

The lack of a quorum is highly unusual for a Supreme Court hearing, a statement from the European Union said. Not hearing this case has de facto cut off the legal path for remedy.