Vice President Joe Biden was the clear aggressor throughout much of his debate with Paul Ryan.

REUTERS/John Gress

ice President Joe Biden and Rep. Paul Ryan (R-Wis.) went toe to toe on Thursday night in the first and only vice presidential debate. Moderated by Martha Raddatz of ABC News, the debate covered both domestic and foreign policy, and elicited a spirited back-and-forth between the two candidates. Biden was under pressure to make up ground after President Obama's listless debate performance against Mitt Romney, while Ryan was hoping to build on the post-debate momentum his campaign has enjoyed. Here, four initial takeaways from the debate:

1. Biden was clearly on offense
Biden uttered the meme-worthy word of the night, accusing Ryan of spewing "malarkey" in his criticisms of the Obama administration's response to the terrorist attack on the U.S. consulate in Benghazi, Libya. Biden went on to say Ryan was full "of stuff," and even scoffed at Ryan's self-comparison to John F. Kennedy. After the vice president laughed that the GOP tax plan was "not mathematically possible," Ryan countered: "It is mathematically possible. Jack Kennedy lowered taxes and raised revenue." Channeling Lloyd Bentsen, Biden incredulously exclaimed, "Oh, now you're Jack Kennedy?"

2. And he fired up the base
Biden's aggressive posture, which ran the risk of turning off some viewers, surely galvanized the Democratic base, which had been demoralized by Obama's failure to attack Romney in their debate, as well as by Romney's surge in the polls. Some reactions from Twitter:

This is a great debate. Solid performance from Ryan, but Biden has clearly surprised Ryan by his strength of discourse.

— Matt Busigin (@mbusigin) October 12, 2012

Whether or not this Biden performance helps Obama, you could sell bootleg DVDs of it to Dems for $20

— daveweigel (@daveweigel) October 12, 2012

Dan Senor, Ryan advisor, hits Biden on eye rolls, calls his delivery a "distraction," a common GOP theme in spin room so far

— john r stanton (@dcbigjohn) October 12, 2012

I'm beginning to comprehend the Obama-Biden campaign's good cop-insane cop strategy.

— Molly Ball (@mollyesque) October 12, 2012

3. But Ryan mostly held his own
The GOP congressman at times appeared to be overwhelmed by Biden's raw, free-wheeling style, but the young Tea Party darling kept his composure throughout the debate. Indeed, if voters respond negatively to Biden's frequent interruptions and bursts of laughter, Ryan's calmer presence on the stage could reap some benefits. And Ryan won applause for his explanation of his anti-abortion position, telling viewers that he now calls his daughter "Bean" because the first time he saw her on an ultrasound that was her shape.

"I don't see how a person can separate their public life from their private life, from their faith." - Ryan

— Alexandra Jaffe (@ajjaffe) October 12, 2012

Ryan's bean story beautiful

— Roben Farzad (@robenfarzad) October 12, 2012

4. Martha Raddatz did a stellar job
In the first debate, veteran journalist Jim Lehrer was heavily criticized for overseeing an unruly debate and failing to keep the candidates on topic. In contrast, Raddatz's debate was a tightly run ship, and she asked smart follow-up questions that put both candidates on the spot. Most importantly, the more regulated format made for a more coherent debate for viewers.

RT @fmanjoo: This is a good debate. It's substantive, it's pointed, it's full of fact-checking. It's really good.

— Slate (@Slate) October 12, 2012

Raddatz is doing a fantastic job moderating this debate.

— Jamelle Bouie (@jbouie) October 12, 2012

I'm a defender of Lehrer's performance in the first debate, but Martha Raddatz is doing a really excellent job here.

— Ezra Klein (@ezraklein) October 12, 2012