HONG KONG — Malaysia scheduled national elections for May 5 on Wednesday, setting the stage for the biggest test of the governing party’s dominance since the country gained independence from Britain more than five decades ago.

The country’s elections chairman, Abdul Aziz Yusof, said candidates would be nominated April 20, allowing for a two-week campaign.

The elections come as Prime Minister Najib Razak has been struggling to hold together the multiethnic coalition, known as the National Front, that has long governed the country. That coalition is composed of three parties that define themselves along racial lines: one for Malays, the country’s largest ethnic group; one for Chinese; and one for Indians.

Recent opinion polls have suggested that Mr. Najib holds a slim majority, with the National Front losing its once-powerful edge as ethnic Chinese have abandoned the coalition. Ethnic Chinese voters who have long supported the governing coalition have shown dissatisfaction with the longstanding preferences given to ethnic Malays in land purchases and bank loans, as well as in university admissions.

Mr. Najib’s most formidable opponent is Anwar Ibrahim, a former deputy prime minister running with the People’s Alliance, which in 2008 balloting captured 5 of Malaysia’s 13 states.

In a statement issued Wednesday, the Malaysian government said Mr. Najib welcomed the elections and the chance to make his case to voters.

“This election is a choice between sticking with a competent, reform-minded government and risking our prosperity on a fractious, inexperienced opposition, whose manifesto doesn’t add up,” the statement said.

The announcement of a date for the elections came one week after Mr. Najib announced that he was dissolving Parliament in a speech on national television in which he sounded defensive.

“Don’t gamble the future of your children and Malaysia,” he said in the address. “Think and contemplate as much as you can before making a decision, because that will determine the direction of the country and also your grandchildren’s future.”

The two-week campaign period is shorter than the 21-day period that an electoral reform group, Bersih, had recommended. But political parties have already begun campaigning.

Mr. Najib has one major advantage: the governing coalition’s longstanding influence over major media outlets. On Wednesday, the Web site of The New Straits Times, a leading English-language newspaper, prominently featured an article suggesting that Mr. Anwar, the opposition candidate, “did not have a firm stand on matters pertaining to Islam” despite the fact that he “portrayed himself as an Islamic figure.”