Watch Susan Collins and Jon Ossoff's testy voting-rights exchange that drew senators' applause

Jan. 20—The nation's youngest senator squared off in a 10-minute debate with U.S. Sen. Susan Collins in a Wednesday exchange on legal history notable for its fine detail and becoming personal.

It came as the Senate held nearly a full day of debate over Democrats' signature voting overhaul. The majority party was trying to weaken the 60-vote threshold to filibuster legislation to pass their bill by a simple majority, but they were thwarted — as expected — by two Democrats who broke ranks to vote with all Republicans including Collins to block the measures.

Earlier in the day, Sen. Jon Ossoff, D-Georgia, called out the Maine senator and three other Republicans who voted in 2006 to reauthorize the Voting Rights Act of 1965, juxtaposing that with their opposition to the Democrats' current package.

A key part of the 1965 law that required the Justice Department to clear election-law changes made in states that have a history of discrimination against minority votes was gutted by the U.S. Supreme Court in a 2013 ruling that said Congress could come up with a new formula governing that process. Republicans have opposed doing that since then, so it has languished.

The John Lewis Voting Rights Advancement Act, one of the two measures that Democrats want to pass, would restore that mandate and update the formula, though it would go further by also subjecting voter identification requirements and other changes in all states to federal review.

Ossoff's initial comments came with Sen. Angus King, I-Maine, presiding. Collins took umbrage, coming onto the floor in the evening to wonder whether Ossoff was confusing the current bill with the 2006 one. She referenced the 34-year-old freshman senator's age, saying she wasn't sure if he "was even born in 1965."

Collins reaffirmed her support for the seminal voting rights bill and argued the current 735-page bill went far beyond the five-page bill she backed more than 15 years ago.

"I think it is sad that he implied otherwise about our support for such important civil rights legislation," she said of Ossoff.

Ossoff returned to praise Collins' background, but he explained he meant to point out an "inconsistency" between her stances then and now. She shot back to note that the federal government was challenging more restrictive Texas and Georgia voting laws under Section 2 of the 1965 law, then Ossoff came back to note the sections that had been weakened.

"If Section 4 and Section 5 were also vital when you voted to reauthorize them in 2006, why aren't they vital today?" he asked.

After Collins finished, Sen. Jeff Merkley, D-Oregon, called the debate one of the most substantive he has heard during his tenure, leading senators to break out in applause.

The Associated Press contributed to this report.