MINSK, Belarus – Thousands of opposition supporters gathered in the center of the Belarus’ capital Monday for a second night, hoping their protest would help overturn a presidential election that the U.S. said was flawed by a “climate of fear.”

Their numbers were smaller than on election night, and prospects for a Ukraine-style “Orange Revolution” seemed remote. But with overnight temperatures at 28 degrees Fahrenheit, protesters set up a dozen small tents and vowed to turn the demonstration into a round-the-clock presence.

The small but assertive move could rally others to the cause. But it could also prove unacceptable to authorities. Officials put on a show of force, with busloads of riot police fanning out into nearby streets and courtyards and preventing people from approaching the main square.

Police had only a small presence at the protest the previous night, when an estimated 10,000 people braved the freezing cold and snow to register their outrage after authoritarian President Alexander Lukashenko was declared the overwhelming winner of Sunday’s elections.

Lukashenko asserted Monday that his foes had failed to topple him in a foreign-backed “revolution.”

International observers said the vote fell short of democratic standards. Europe’s main human rights organization said it was a “farce,” and the United States called for a new election. Lukashenko’s main opponent refused to accept the outcome, calling the longtime leader an “illegal, illegitimate president.”

However, the leverage of the international community seemed limited, and even many of the protesters appeared to have little appetite for a prolonged vigil and a possibly violent confrontation.

The election result, if it stands, would entrench the status of Belarus as one of the least independent of the former Soviet republics.

Some 5,000 gathered in Oktyabrskaya Square in the capital, about half the number that came out Sunday night for a protest whose size was extraordinary in a tightly controlled country where police have cracked down swiftly on unsanctioned opposition gatherings.

The diminished crowd suggested to many that the opposition was losing momentum.

But Alexander Milinkevich, the main opposition presidential candidate and symbolic heart of the protests, called on the demonstrators to gird for a lengthy campaign. He is demanding an election rerun.