U.S. Republican presidential candidate Mitt Romney opened a new campaign offensive Monday, asserting that President Barack Obama conducts his foreign policy “at the mercy of events” overseas.

Mr. Romney criticized the Democratic incumbent at a rally in Colorado, one of several states where voters are closely divided six weeks ahead of the November 6 election. Mr. Romney derided the president's comment in a televised interview Sunday that there would be “bumps in the road” for Arab countries transforming dictatorships into democracies.

The Republican challenger said the bloodshed and violence in the Arab world “are not 'bumps in the road.' These are human lives. It's time for a president who will shape events in the Middle East.”

Mr. Romney is planning a speech on education policy in New York Tuesday before heading to Ohio, another electoral battleground state, to campaign with his vice presidential running mate, Wisconsin congressman Paul Ryan. That will be followed by a trip to the mid-Atlantic state of Virginia.

Meanwhile, the president and his wife Michelle are heading to New York, where Mr. Obama will address the opening of the 67th session of the United Nations General Assembly Tuesday morning.

Mr. Romney has been criticized by many Republicans for spending more time raising campaign money than meeting voters. Mr. Romney told reporters Sunday that his fundraising efforts will be “a little quieter going forward.”

His standing in voter surveys has fallen due to a series of major missteps in recent weeks.

Mr. Romney and Mr. Obama will take part in the first of three face-to-face debates on October 3.