Delaware Sen. Joseph Biden took on the role of Democrat Barack Obama's running mate Saturday, attacking Republican candidate John McCain and making clear that whatever doubts he'd previously expressed about Obama's readiness were gone.

SPRINGFIELD, Ill. — Delaware Sen. Joseph Biden took on the role of Democrat Barack Obama’s running mate Saturday, attacking Republican candidate John McCain and making clear that whatever doubts he’d previously expressed about Obama’s readiness were gone.

In an appearance with Obama, Biden called him an inspiration to millions with “steel in his spine” and “a clear-eyed pragmatist who will get the job done.”

He went after McCain, a longtime friend, as having given “in to the right wing of his party and yielded to the very Swift Boat politics he once so deplored.”

He also said McCain would continue President Bush’s policies and chided that McCain is so wealthy and insulated from average people’s concerns that his version of making difficult kitchen-table decisions is that “he’ll have to figure out which of his seven kitchen tables to sit at.”

The appearance was the culmination of a frenetic week of speculation over who would get the vice-presidential nod from Obama. In the end, it was a longtime Washington figure whose Roman Catholic faith and blue-collar credentials — his net worth of $150,000 is decidedly middle class in the millionaire-laden U.S. Senate — seemed intended to shore up Obama’s electoral weak spots.

Democratic leaders embraced Biden’s selection, noting that he has served in the Senate for 35 years and has chaired the Judiciary Committee and the Foreign Relations Committee.

The Republican Party line was to call the choice hypocritical, highlighting Biden’s campaign contributions from special-interest groups whose influence Obama said he wants to reduce and Biden’s early assertions, when he was competing with Obama for the Democratic nomination, that Obama, 47, wasn’t ready for the job.

Obama, introducing Biden outside the Illinois Old State Capitol, noted that Biden, 65, was a Roman Catholic born in Scranton, Pa., who had been raised working class. Responding to criticism that Biden was a Washington insider who’d first been elected to the Senate in 1972, Obama said the senator was “uniquely suited” to share the ticket with him.

“For decades he has brought change to Washington but Washington hasn’t changed him,” Obama said.

Obama aides were vague about the timing of his decision.

Two Biden associates said he got the call from Obama while undergoing a root canal Thursday and interrupted the procedure to accept the candidate’s invitation to be his running mate.

In the end, Obama’s choices came down to Biden, Indiana Sen. Evan Bayh and Virginia Gov. Tim Kaine, said several people involved in the deliberations. Kansas Gov. Kathleen Sebelius also was a strong contender, but dropped out as Obama focused on the other three. New York Sen. Hillary Rodham Clinton never was seriously considered, said two officials involved with the search.

Obama’s campaign had promised supporters they would be the first to know if they signed up to receive text messages. But Biden’s selection leaked late Friday, hours before the text message went out. Then, glitches meant some who signed up received their messages late or not at all.

Material from The Associated Press is included in this report.