Washington  - The volunteer at the shelter for homeless teens pushed up his sleeves and took up a roller of blue paint.

"This is good practice cause I'm moving to a new house tomorrow," he joked in playful banter with his fellow volunteers.

But this was no ordinary do-gooder. This was Barack Obama, who will move into the White House Tuesday as the 44th president of the United States.

Brasilia  - Outgoing US President George W Bush called Brazilian President Luiz Inacio Lula da Silva to say goodbye Monday, Brazil's presidential spokesman Marcelo Baumbach said.

The conversation was said to have lasted 10 minutes. Bush - who is set to hand over power to Barack Obama Tuesday - invited Lula to visit him in his home state, Texas, while Lula invited Bush to go fishing in Brazil.

Washington  - With just one full day left in office, US President George W Bush spent Monday holding farewell telephone calls with more than a dozen world leaders, the White House said.

Tehran  - Former Iranian president Mohammad Khatami will run in next June's presidential election and challenge President Mahmoud Ahmadinejad, the Fars news agency reported Monday.

Fars said that after a meeting of leading reformist activists in Tehran, Khatami has officially proclaimed his nomination for the June 12 presidential elections.

Fars further reported that Khatami will probably choose former prime minister Mir-Hossein Moussavi as his vice president.

Washington  - One day before his inauguration as the United States' first African-American president, Barack Obama rolled up his sleeves and joined other Americans in celebrating the birthday of civil rights leader Martin Luther King Jr with acts of community service.

The outpouring of generosity comes amid final preparations in Washington for the lawmakers, dignitaries and as many as 2 million Obama supporters who were expected to flood the capital's National Mall for the swearing-in ceremony on Tuesday.

Harare  - In a make-or-break moment for the country's historic powersharing deal, Zimbabwean President Robert Mugabe and opposition leader Morgan Tsvangirai came together Monday to try to iron out their differences over the formation of a unity government.

Their talks, aimed at ending a four-month impasse on the implementation of the September accord, are being brokered by a three- man team from the Southern African Development Community (SADC), led by South African President Kgalema Motlanthe.