WASHINGTON - Barack Obama heads back to the scene of his first breakthrough triumph today, hoping to use Iowa as a backdrop to announce that he's gained enough pledged delegates to all but clinch the Democratic presidential nomination.

The Illinois senator was looking for a split decision in two primary states -- he's leading in Oregon and trailing in Kentucky -- that aides predicted would put him ahead to stay among delegates elected in caucuses and primaries.

"When the votes are counted in Oregon and Kentucky, we could secure a majority of delegates elected by the voters," Obama campaign manager David Plouffe said Monday.

The Illinois senator planned a rally tonight in Des Moines, where his victory in precinct caucuses Jan. 3 first signaled that he could defeat front-runner Hillary Rodham Clinton.

Clinton's camp called it arrogant and presumptuous.

"Senator Obama's plan to declare himself the Democratic nominee tomorrow night in Iowa is a slap in the face to the millions of voters in the remaining primary states and to Senator Clinton's 17 million supporters," Clinton spokesman Howard Wolfson said Monday.

The New York senator's campaign stressed that Obama won't able to clinch the nomination today even if he does secure the majority of pledged delegates. The total number of delegates needed for the nomination is 2,026. As of Monday, Obama had 1,915 -- elected and unelected, according to an Associated Press tally. Kentucky's primary allots 51 delegates, and Oregon 52.

Obama gained two more unelected superdelegates Monday -- Sen. Robert Byrd of West Virginia and Washington State Democratic Party Chairman Dwight Pelz.

The milestone Obama's campaign claims is in reach today is a majority of pledged delegates. Obama goes into today's contests with 1,610.5 pledged delegates, won in primaries and caucuses. He needs 17 more to reach a majority of the 3,253 pledged delegates available. Clinton has 1,443.5 pledged delegates, according to the AP.

McCAIN BLASTS OBAMA: Republican John McCain accused Obama of inexperience and reckless judgment for saying Iran does not pose the same serious threat to the United States as the Soviet Union did in its day.

McCain commented Monday in Chicago, Obama's home turf.

"Such a statement betrays the depth of Senator Obama's inexperience and reckless judgment. These are very serious deficiencies for an American president to possess," McCain said.

He was referring to comments Obama made Sunday: "Iran, Cuba, Venezuela -- these countries are tiny compared to the Soviet Union. They don't pose a serious threat to us the way the Soviet Union posed a threat to us. And yet we were willing to talk to the Soviet Union at the time when they were saying, 'We're going to wipe you off the planet.' "