By John Whitesides, Political Correspondent
Republican John McCain, still facing conservative opposition, promised to unite his party as his coast-to-coast "Super Tuesday" wins in key states put him on the verge of clinching the nomination and capping a stunning political comeback.
Obama and Clinton battled to a draw on Super Tuesday, with Obama winning 13 states and Clinton eight, including the big prizes of California and New York. Their delegate race also was almost even, propelling the fight toward the next round of seven Democratic contests in the next six days.
"I loaned it because I believe very strongly in this campaign," she told reporters at her headquarters in Arlington, Virginia, a state that votes next Tuesday.
Also, as a show of solidarity some Clinton staff members have volunteered to go without pay, a Clinton spokesman said.
"We've got many more rounds to fight and you know I think that Senator Clinton remains the favourite because of the enormous familiarity people have with her and the institutional support she has," Obama told reporters in Chicago.
The Democrats will square off in Louisiana, Nebraska and Washington on Saturday, Maine on Sunday, and Virginia, Maryland and the District of Columbia on Tuesday -- turf that could favour Obama.
Under Democratic Party rules, delegates are proportioned by results state-wide and in individual congressional districts. This enables both candidates to roll up big delegate totals even in states they lose.
That increased the likelihood the hotly contested race could last well into March contests in Texas and Ohio, an April contest in Pennsylvania and perhaps all the way to the party convention in late August.
Various estimates put the Democratic race for pledged delegates in an essential deadlock, with each campaign claiming a slight edge. Clinton leads among "super-delegates," the elected officials and party insiders who can switch allegiance at will.
"We will unite the party behind our conservative principles and move forward to the general election in November," McCain told reporters in Phoenix, acknowledging conservative concerns about his past stances on immigration, tax cuts and other issues.
Republican rivals Mitt Romney and Mike Huckabee vowed to fight on but could face questions about their viability. Romney won seven states and Huckabee five on Tuesday.
McCain, a former Vietnam prisoner of war who lost the Republican primary race in 2000 to George W. Bush, dropped plans for a possible trip to attend an international security conference in Germany so he could focus on his campaign.
Romney also is scheduled to address the conference of conservative activists in Washington on Thursday, while Huckabee was to speak there on Saturday.
(For more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at http://blogs.reuters.com/trail08/)
