BAKU, Azerbaijan (AP) – Thousands of demonstrators chanting “Freedom” and carrying portraits of President Bush marched across Azerbaijan’s capital Saturday, demanding the resignation of the government and free parliamentary elections – in the biggest protest in years.

The protest of about 20,000 marchers, the second such rally in as many weeks, was organized by three leading opposition parties that formed the Azadlig (Freedom) bloc to run for parliamentary elections set for November.

About 200 police in full riot gear stood guard around a central square where protesters gathered. Brief clashes erupted when demonstrators tried to push police away from the square and officers in riot gear fought back with truncheons. Last month, police beat back protesters who tried to hold a banned rally in Baku and detained dozens.

Tensions have been building steadily in this oil-rich Caspian Sea nation in the run-up to the elections, leading some observers to predict that Azerbaijan could see a massive uprising similar to those that toppled unpopular regimes in other ex-Soviet nations of Georgia, Ukraine and Kyrgyzstan during the past 18 months.

Supporters of the Musavat party, the People’s Front of Azerbaijan and the Democratic Party of Azerbaijan chanted “Freedom” and “Free Elections” and carried pictures of President Bush, seen as inspiration for the earlier democratic revolutions in the former Soviet republics of Georgia and Ukraine.

Bush visited Georgia’s capital of Tbilisi last month and told a cheering crowd of tens of thousands of people that Georgia is proving to the world that determined people can rise up and claim their freedom from oppressive rulers.

Azerbaijan’s opposition bloc has chosen orange as its campaign color – the color that was also used by the Ukrainian opposition during mass protests dubbed “Orange Revolution” that helped pave way for the victory of a Western-backed candidate over a Russia-backed rival.

Many participants in Saturday’s rally wore orange T-shirts and baseball caps and carried orange flags.

The opposition demands election law reforms and access to state-controlled television. They also have accused authorities of rigging the October 2003 presidential election when President Ilham Aliev succeeded his late father, Geidar Aliev, and demanded changes to prevent fraud in the parliamentary vote.

That vote set off clashes between police and opposition demonstrators protesting vote-rigging, in which one person died and nearly 200 were injured.

Azerbaijan, a mostly Muslim country of 8.3 million, is the starting point of the key pipeline that Washington says will reduce dependence on oil from the Middle East. The country also is a U.S. ally in the war on terrorism, with troops in Iraq.