The next president will face a mountain of challenges, including reining in deficit spending, managing U.S. involvement in Iraq and Afghanistan, controlling illegal immigration and restraining the spiraling costs of Medicare and Social Security. And that's just the start.

The 44th president should have a strong resume of government experience. When the nation's voters go to the polls in November to choose that leader, the major-party candidates should be those who require the least on-the-job training. Of the contenders remaining in the Republican and Democratic races, the most experienced are Republican Sen. John McCain and Democratic Sen. Hillary Clinton.

McCain, of Arizona, now is on a trajectory to easily win his party's nomination. His major competitor, former Massachusetts Gov. Mitt Romney, dropped out Thursday, and former Arkansas Gov. Mike Huckabee and Texas Rep. Ron Paul now lag far behind him in the delegate count.

McCain has a lifetime of public service, starting in the Vietnam War. After his Navy plane was shot down over North Vietnam, McCain was held as a prisoner of war for 5 1/2 years and endured severe torture.

He was elected to Congress in 1981 as a member of the House and has been in the Senate since 1987. He's the ranking Republican on the Armed Services Committee and serves on the Commerce, Science and Transportation and the Indian Affairs committees.

Clinton's background also features years of public service. She has been in the Senate since 2001, winning election in New York as she was reaching the end of her time as the nation's first lady. In addition to what sometimes was characterized as a co-presidency with her husband, during his two terms in office, she was first lady in Arkansas for 12 years.

She hopes to become the first woman to win a major-party presidential nomination. While her husband was president, she was one of the most politically involved first ladies in U.S. history. Her activism on a variety of issues earned her the kind of loyalty and opposition usually reserved for presidents.

In the Senate, Clinton serves on the Armed Services, Environmental and Public Works, Health, Education, Labor and Pensions committees as well as the Senate's Special Committee on Aging.

Her opponent, Sen. Barack Obama of Illinois, has mounted an impressive campaign for the nomination, but Obama, who was an Illinois state senator before his election to the U.S. Senate in 2004, lacks his rival's experience.

Unlike some years, this year Ohio will be not be an afterthought in the presidential primaries. Though McCain's lead is substantial, the Democratic race remains very close, so the Ohio vote on March 4 could be decisive.