MEXICO CITY — The newly declared president-elect, Felipe Calderon, began building his government yesterday, and his supporters called on backers of the leftist Andres Manuel Lopez Obrador to end weeks of national protests over the disputed July 2 election.

Mr. Calderon held a series of private meetings early yesterday and was scheduled to meet with President Fox later in the day to discuss the transition to his new government and next year’s budget, Mr. Fox’s spokesman, Ruben Aguilar, said. Mr. Aguilar said President Bush called Mr. Fox early yesterday to congratulate him on the end of a lengthy electoral process and the “strength of Mexico’s democracy.”

But weeks of angry rhetoric and tensions were likely to continue, as Mr. Lopez Obrador vowed to never recognize Mr. Calderon as Mexico’s leader and said he would instead create his own parallel government. Trying to counter more than a month of protest camps in favor of Mr. Lopez Obrador, Mr. Calderon’s supporters planned to form a human chain yesterday to urge the nation to support a peaceful transition.

Civic groups and unions published full-page ads in Mexico’s principal newspapers yesterday calling for peace and unity. In an interview late Tuesday with Mexico’s Televisa television network, Mr. Calderon said he would begin forming a government “immediately” but would take his time choosing a Cabinet, announcing his choices “very likely in the hours close to the swearing-in” on December 1.

He said he would be looking for “honest people … capable people, people who are loyal to the [administration’s] plan and to Mexico.”

Always confident of his eventual victory, Mr. Calderon has been quietly drawing up transition plans since the days that followed the election. Mr. Lopez Obrador’s supporters and allied parties have said they will try to block the handover, just as they kept Mr. Fox from giving his state-of-the-nation address Friday.

The Federal Electoral Tribunal’s decision rejected Mr. Lopez Obrador’s allegations of systematic fraud and awarded Mr. Calderon the presidency by 233,831 votes out of 41.6 million cast — a margin of 0.56%. The ruling cannot be appealed.

Mexico has a history of incidents involving electoral fraud, dating back to the early 20th century.

In 1910, riots broke out after elections widely believed to be rigged gave another term to Porfirio Diaz, who ruled Mexico for 30 years with an iron fist. Officials said his opponent Francisco Madero had only received a few hundred votes in the entire country. Mr. Madero called the Mexican people to take up arms and fight against the government, launching the Mexican Revolution.

In 1940, the Institutional Revolutionary Party, or PRI, candidate, Manuel Avila Camacho, won with 93.9% of the vote over independent General Juan Andrew Almazan in an election marred by violent clashes and credible accusations of vote fraud. A number of Almazan’s followers were persecuted and killed.

In 1958, PRI candidate Adolfo Lopez Mateos defeated the National Action Party, or PAN, candidate, Luis Alvarez, with 90.56% of the vote. Mr. Alvarez was not allowed any radio time and was once jailed during the campaign on the charge of “being an opposition candidate.”

In 1988, early returns in the presidential elections showed leftist Cuauhtemoc Cardenas leading, but a computerized election system mysteriously failed, and when it was reconnected hours later, PRI candidate Carlos Salinas had won by a narrow margin.

Yesterday, Mr. Calderon appeared confident and spoke forcefully in an appearance before cheering supporters hours after the court’s decision was announced.

The 44-year-old former energy secretary and career politician promised during his campaign to follow his predecessor’s free-market, pro-business policies in order to create jobs, keep the economy growing and fight poverty.

Mr. Calderon announced three major initiatives aimed in part at winning over those who did not vote for him: reducing poverty, fighting crime, and improving the economy. He also reiterated “my respect and my willingness to dialogue” with Mr. Lopez Obrador, telling Televisa, “I recognize that he has a genuine concern for the situation of poverty in which millions of Mexicans are living. But Mr. Lopez Obrador rejected Mr. Calderon as president-elect.

“I do not recognize someone who tries to act as the chief federal executive without having a legitimate and democratic representation,” he told thousands of supporters in Mexico’s main Zocalo plaza who chanted: “Felipe, the people don’t want you!”