AP Photo

Little more than three weeks before the presidential election, problems that include insecurity and fears of fraud are raising concerns about the credibility of the race, which President Obama has called the most important event in Afghanistan this year.

Supporters of Abdullah Abdullah, the only serious challenger in the presidential race, gathered in Kabul on Monday to greet him with songs and balloons. More Photos »

In Helmand, the election will take place only in safe zones. More Photos >

With Taliban insurgents active in half the country, many Afghans remain doubtful that the Aug. 20 election will take place at all. The Taliban issued a statement last week calling for a boycott, a threat that could deter voters in much of the...