pressure really on and governor romney tried to keep it coming today taking aim at the president's foreign policy and abc's david muir is here with that. David? Governor romney with harsh criticism... See More
pressure really on and governor romney tried to keep it coming today taking aim at the president's foreign policy and abc's david muir is here with that. David? Governor romney with harsh criticism saying hope is not a strategy. So tonight hear romney's speech and we ask what are the real policy differences? Mitt romney with harsh words for the president offering his own view of a greater american role around the world. Our friends and allies across the globe don't want less american leadership, they want more. Reporter: Perhaps the biggest distinction, on syria. Romney arguing the u.S. Should partner with other countries to help arm the rebels to defeat president bashar assad. Then ensure they obtain the arms they need to defeat assad's tanks and helicopters and fighter jets. Reporter: Romney's aide saying he is not suggesting the u.S. Arm the rebels directly. President obama has opposed providing weapons to the rebels partly out of concern that those could bind up in the hands of terrorists. On iran mitt romney earlier this year saying this. If we re-elect barack obama, iran will have a nuclear weapon. Reporter: But today was unclear what exactly romney would do that would be different. The obama administration imposing tough sanctions already. I will not hesitate to impose new sanctions on iran and will tighten the sanctions we currently have. Reporter: The obama campaign asking just what would those new sanctions be and on libya after the attack in benghazi that killed four americans including ambassador chris stevens, blistering words for the obama administration. This latest assault can't be blamed on a reprehensible video insulting islam despite the administration's attempts to convince us of that for so long. No, the administration has finally conceded these were the deliberate work of terrorists. Reporter: Romney said today he would vigorously pursue the terrorists. President obama has said he is doing the same thing and the obama campaign trying to remind voters of romney's first reaction criticizing the president as the attack was unfolding. Our u.S. Diplomats were attacked in libya the oba-- up in virginia. The campaign arguing voters should know that romney's time line for afghanistan is the same that romney wants to get more deeply involved in syria than the president and on iraq they point out romney argued the full withdrawal of troops from iraq was a distake. Election day four weeks from tomorrow. David and jake tapper will be here with george stephanopoulos and me. The whole pal team when the vice presidential contenders face off one on one the candidates debate moderated by our own award-winning martha raddatz. And that's thursday at 9:00 eastern, 6:00 pacific.
This transcript has been automatically generated and may not be 100% accurate.