WASHINGTON: US lawmakers in the House of Representatives debating the National Defence Authorisation Act voted 412-1 for an amendment that could block up to $650 million in proposed payments to Pakistan unless Islamabad lets coalition forces resume shipment of war supplies across its territory.

The lawmakers were debating an annual defence policy bill that seeks $642.5 billion in military spending for the 2013 fiscal year.

The moves came as lawmakers debated more than 140 amendments to the policy bill, which seeks $554 billion in base defence spending for the 2013 fiscal year beginning in October and $88.5 billion for the Afghan war and other overseas operations.

War fatigue

The pressure for an accelerated withdrawal from Afghanistan came ahead of a two-day Nato summit in Chicago starting on Sunday where leaders will discuss the final transition to Afghan security control and the withdrawal of international forces by the end of 2014.

Democratic lawmakers tried to add language to the bill urging Obama to complete an accelerated handover of security to Afghan forces by the end of 2013 and to remove US troops by the end of 2014 — aims consistent with administration planning.

But Republican leaders, who last year narrowly defeated an effort to force Obama to begin planning for withdrawal from Afghanistan, blocked discussion of the Democratic amendment. Instead, they allowed debate on one that called for immediate withdrawal. The measure had little chance of passing and was ultimately defeated.

Lawmakers nearly unanimously endorsed an amendment that would block payment of some $650 million in proposed Coalition Support Funds for Pakistan as long as its borders remain closed to shipments of supplies for international forces.

Islamabad closed the frontier to Nato supply convoys after an air strike in November killed 24 Pakistani soldiers. A US official said on Wednesday the two sides were on the verge of clinching a deal to reopen the supply lines.