DES MOINES - U.S. Sen. Tom Harkin said Friday no candidate should be forced from the presidential race as pressure has built inside the Democratic Party for Hillary Clinton to drop out.

Harkin said he will not throw his endorsement behind either Clinton or Barack Obama before all of the Democratic primary contests are completed on June 3.

Harkin is the highest profile Democrat in Iowa who has yet to back either candidate. He said voters should have a right to cast their votes before he and other superdelegates like him make their choice.

"We set up rules, and I believe that as long as there are people running for president in our party, then every state ought to have a right to vote," Harkin said. "So if a person wants to drop out, well that's up to them. But I don't think we ought to try to force anyone out of a race before the end of the rules."

Contests in Kentucky, Oregon, Puerto Rico, Montana and South Dakota still remain.

Harkin declined to give clues on whom he might support when those contests have wrapped up.

"I'll let you know after June 3rd," Harkin said on a conference call with reporters.

Of Iowa's 11 superdelegates, only Harkin and Iowa Democratic Party Chairman Scott Brennan remain uncommitted. Six of them are supporting Obama, including Iowa Gov. Chet Culver and U.S. Reps. Dave Loebsack and Bruce Braley.

Clinton has three of Iowa's superdelegates in her column, including U.S. Rep. Leonard Boswell.

The 12th superdelegate will be chosen at the party's state convention on June 14th.

Harkin is up for re-election this year and could be holding back his endorsement in an effort not to alienate Democratic voters. But he also has been critical of the process where superdelegates play a role in picking a nominee.

In the last presidential contest, Harkin endorsed former Vermont Gov. Howard Dean in the weeks leading up to the Iowa Democratic caucuses. Dean finished third in the contest.

Harkin said he disagrees with Clinton's contention that the results of the Michigan contest, which she won and Obama did not compete in, should count in the nomination fight.

Harkin said Michigan should not have any part in the process because the state broke Democratic Party rules by holding its contest early.

"They should not be allowed now to come in and somehow vote or have some way of deciding who the nominee is going to be," Harkin said.

Charlotte Eby can be reached at (515) 243-0138 or chareby@aol.com.