Senate Republicans on Friday blocked a 50-billion-dollar Iraq war spending bill because Democrats attached a timetable for US troop withdrawals. The 53-45 vote in favour of the bill fell seven votes short of the 60 needed to move forward based on Senate rules. The House of Representatives, which requires only a simple majority, approved the measure on Wednesday. Senate Democrats, who narrowly hold a majority in the upper chamber, voted 53-45 earlier Friday to defeat a 70-billion-dollar Republican spending bill to fund the wars in Iraq and Afghanistan without troop withdrawal deadlines. President George W Bush strongly opposes congressional deadlines for removing US troops from Iraq and has previously vetoed legislation containing pullout timeframes. The Democrats want to set timelines for bringing the US role in Iraq to an end.