U.S. President Barack Obama and Republican candidate Mitt Romney are taking their campaigns to the key political battleground state of Ohio Tuesday, as they seek to win over voters four weeks before the election.

Mr. Obama will appeal to supporters at Ohio State University in Columbus while Mr. Romney will hold a rally in Cuyahoga Falls, Ohio.

Ohio is one of the so-called swing states that could help decide the outcome of the November election.

The campaigning in Ohio comes as several polls indicate Mr. Romney is gaining ground.

The latest Pew Research Center poll of likely voters shows 49 percent would cast ballots for Mr. Romney if the election were held today, compared to 45 percent for Mr. Obama.

A Public Policy Polling survey shows Mr. Romney ahead of Mr. Obama, 49 percent to 47 percent.

However, the latest Gallup tracking poll shows the president leading Mr. Romney, 50 percent to 45 percent. Mr. Romney's numbers were higher in the previous Gallup poll, conducted after the first presidential debate.

Most observers say Mr. Romney won the October 3 debate. The two presidential contenders will hold a second debate next week, with citizens posing questions on both domestic and foreign issues. A third debate, focusing on foreign policy, will take place later this month.

Despite losing ground in the polls to Mr. Romney following the first debate, Mr. Obama told supporters at a fundraising event Monday night that he “very much” intends to win the election. He urged his backers to be “almost obsessive” in their efforts until election day.

Earlier Monday, Mr. Romney accused the president of being a weak leader, especially regarding the Middle East.

In his first major foreign policy speech of the campaign, Mr. Romney said that under President Obama, the United States has been at the mercy of events rather than using what the Republican challenger called its “great power to shape history.”

He accused the president of failing to lead in Syria, called the U.S. withdrawal of forces from Iraq “abrupt,” and said the United States and Israel are growing apart, which he says has emboldened Iran.

Mr. Romney also said there will be no flexibility with Russia on missile defense in Europe.

The Obama campaign swiftly responded to the Romney speech, saying there is a good reason the president leads Mr. Romney in the polls on national security — citing the end to the war in Iraq and the killing of al-Qaida chief Osama bin Laden.