MANCHESTER, N.H. — Marco Rubio is trying to make his youth an asset in foreign affairs, arguing here Thursday that the nation's security is being compromised by Washington's "outdated political establishment" and that he would be a nimble commander in chief.

Addressing factory workers at Granite State Manufacturing, a plant here that makes cutting-edge robots and other military tools, Rubio, a 44-year-old, first-term senator from Florida, laid out a muscular vision for America's role in the world.

"The nature of warfare is always changing and the leaders of the past are almost always blind to these changes," Rubio said, extending his criticism to "outdated leaders" of both political parties. He called for reinvesting in the military and modernizing its forces.

As Rubio spoke in Manchester, he was missing a vote back in Washington on a defense appropriations bill. Rubio has come under criticism from rival Jeb Bush and other candidates for repeatedly missing votes in the Senate while campaigning for president, though a Rubio spokeswoman, Brooke Sammon, said his absence Wednesday made no difference because the vote was not close. If it had been, Sammon added, Rubio would have returned to Washington.

In his remarks here, Rubio said Hillary Rodham Clinton, the former secretary of state and leading Democratic presidential candidate, would "write the sequel to President Obama's disastrous foreign policy."

"I have the record of judgment, the breadth of experience and the quality of leadership necessary to restore our strength and our security," Rubio said. Discussing a revival of American power abroad, he added: "I am ready to argue this case to America and the world in the years ahead. I will not tire in my efforts, and I will not flag in my optimism for the future."