Decision made at meeting attended by Karzai, the U.K.'s David Cameron and Pakistan's Nawaz Sharif.
Police say 5 were also wounded in the attack on a bus in Ghazni.
"We are very confident that we can vote for this agreement with a large majority," says defense minister.
Roughly 12M people earn meager livings as unskilled day laborers.
Leaves 10 in the race, including heavyweights such as Karzai brother and several former warlords.
Hit rock bottom two years ago, in part over raid that killed Osama bin Laden.
Germany is one of the biggest contributors to the international security force in Afghanistan.
Police had no initial reports on any casualties from the attackl; site houses contractors, diplomats.
Logar Gov. Arsallah Jamal was killed by a bomb that went off as he was delivering a holiday address.
Arsallah Jamal was a close confidant and adviser to President Karzai.