Caution greets Bush's pitch.

By Steve Kraske, The Kansas City Star, Mo. Knight Ridder/Tribune Business News

Feb. 5--OMAHA, Neb. -- President Bush offered warm words to Democratic Sen. Ben Nelson on Friday, telling an arena full of Nebraskans that their senator was "a man with whom I can work."

After a one-hour, campaign-style roundtable on Social Security reform at the downtown Qwest Center, the president loaded Nelson into his limo for more face time on the ride to the airport. Once there, they continued to talk while Air Force One sat whining, ready to go on to Arkansas and Florida.

But Bush didn't close the deal.

Nelson and other Democratic senators from states that the Republican president carried last year are seen as crucial allies if Bush is to push through the cornerstone of his plan -- private retirement accounts.

"I fully recognize a personal retirement account is not the only thing needed ... to solve Social Security permanently," Bush told his audience. "But it's a part of a solution."

The president's traveling presentation, however, left Nelson resolutely …