WASHINGTON, April 27 (UPI) -- Plans outlined by the three main U.S. presidential contenders will increase the federal deficit, adding to the national debt significantly, budget experts say.

Arizona Sen. John McCain, the presumptive GOP nominee, is proposing deep tax cuts, while the two Democrats vying to be president are proposing a vast array of new government programs, The New York Times (NYSE:NYT) reported Sunday.

Robert Bixby, executive director of the Concord Coalition, a nonpartisan group that advocates deficit reduction, said whoever wins the Oval Office will have an effect on the nation debt, which has reached $9.1 trillion from $5.6 trillion at the start of 2001.

"With the proposals they have on the table, it looks to me like all three would make it deeper," Bixby said of the national debt.

Experts say McCain's tax plan appears the most likely to widen the deficit.

The nonpartisan Tax Policy Center in Washington found his tax and budget plans, if enacted as proposed, would add at least $5.7 trillion to the national debt over the next 10 years.

Plans by Democrats Sens. Hillary Clinton of New York and Barack Obama of Illinois would impact the deficit about two-thirds less than McCain's plan, the newspaper reported.