The election will give the US a new chance to fix relations with Kabul.
They are in deep discord after more than 12 years of war and repeated fallings-out between the White House and President Hamid Karzai.
The Obama administration will seek the approval of Karzai's successor on an agreement that would allow up to 10,000 US troops to stay in the country after this year.
The White House also will face questions from lawmakers weary of spending taxpayer money in Afghanistan amid endemic corruption.