He says that he is doing so because the electoral commission and process is hopelessly corrupt, and that they have refused to do anything to correct the issue.

He is correct, the changes proposed for the runoff made fraud more, rather than less, likely:

Despite having fewer poll workers and a declining security situation, Afghanistan’s election commission announced Thursday it would increase the number of polling centers for the presidential runoff.

While some analysts suspect the goal is to achieve high-enough turnout for a credible result, the ambitious plan heightens concerns that fraud will once again mar the election

The experts are wrong. Fraud is the goal, not increased turnout.

Unsurprisingly, the electoral commission, which is packed with Karzai cronies, has declared him the elected president.

I hope that the statement from the US embassy is just pro forma:

“We congratulate President Karzai on his victory in this historic election,” said a statement from the United States Embassy in Kabul, “and look forward to working with him, his new administration, the Afghan people and our partners in the international community to support Afghanistan’s progress towards institutional reforms, security and prosperity.”

Because if they see a stolen election in the context of a civil war as legitimate, it’s Diem in Vietnam all over again.