Sen.  John McCain addresses the Economic Club of Canada, in Ottawa, Canada, 20 June 2008

Republican presidential candidate John McCain traveled to Canada Friday and delivered a speech supporting the North American Free Trade Agreement, NAFTA, a pact that Democratic hopeful Barack Obama has criticized.

McCain told a group of business leaders in Ottawa that if he is elected, the United States will honor its international commitments to NAFTA.

During the Democratic primary, Obama said the U.S. should negotiate with Canada and Mexico to add tougher environmental and labor rules.

On Friday, Obama launched an attack against McCain's proposal to allow offshore oil drilling in U.S. coastal waters.  Obama said the proposed drilling would not lower fuel prices for many years.

McCain opposed such drilling when he ran for president in 2000, but this week he said he supports giving individual states the right to decide whether to allow oil drilling.

Barack Obama, right, and Hillary Rodham Clinton share the stage at the Compassion Forum in Grantham, Pennsylvania, 13 April 2008 (file photo)

Separately, the Obama campaign announced that the Illinois senator will campaign next week for the first time with former rival Hillary Clinton.  Obama's campaign said the two senators will campaign together June 27, but it released no further details.

The two also are scheduled to meet in Washington Thursday, when Clinton is expected to introduce Obama to some of her top campaign contributors.  These meetings are a step towards unifying the Democratic Party after a long and bruising primary campaign in which Obama clinched enough delegates to secure the party nomination.

Some information for this report was provided by AFP, AP and Reuters.