Democratic presidential hopeful Sen. Barack Obama (D-Ill.) ended the veepstakes suspense early Saturday morning by tapping fellow Sen. Joseph Biden (D-Del.), one of the chamber’s strongest national security voices, to serve as his No. 2 heading into the general election.

Presumptive GOP nominee Sen. John McCain (R-Ariz.) immediately responded by launching a new television ad pointing to Biden’s criticism of Obama’s foreign policy experience while Biden was himself running for president and quoted Biden saying he would be “honored” to run with McCain for president.

In a statement sent shortly after Biden was tapped, McCain said: “There has been no harsher critic of Barack Obama’s lack of experience than Joe Biden. Biden has denounced Barack Obama’s poor foreign policy judgment and has strongly argued in his own words what Americans are quickly realizing — that Barack Obama is not ready to be President.”

Biden had been on the short list of contenders for the job, along with Sen. Evan Bayh (D-Ind.) and Virginia Gov. Tim Kaine (D). Biden brings to the ticket nearly four decades of Congressional experience and a foreign-policy-heavy résumé as chairman of the Senate Foreign Relations Committee. Biden was also a one-time contender for the 2008 presidential nomination, but dropped out after securing little support in Iowa.

Obama made the announcement in an e-mail to supporters early Saturday. The two Senators will appear at a rally today at 3 p.m. EST in Springfield, Ill., the same spot where Obama launched his presidential bid more than a year ago.

In a statement on his Web site and accompanying plea for campaign cash, Obama outlined Biden’s strengths on the ticket. Obama, a first-term Senator with little background in foreign affairs, has been criticized for lacking the muscle necessary to serve as commander in chief.

“Joe Biden brings extensive foreign policy experience, an impressive record of collaborating across party lines, and a direct approach to getting the job done,” Obama’s Web site reads. “We have our team, but we also have our work cut out for us. Barack Obama and Joe Biden are the leaders who will bring the change our country needs. But they can’t do it alone. Show your support for the Obama-Biden ticket by making a donation today.”