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Mike Pence demonstrated the benefit of preparing for a debate – the question is whether Donald Trump will heed the lesson.

The Indiana governor delivered a smooth performance at Tuesday’s vice presidential debate, lobbing attacks at Hillary Clinton with far greater effect than Trump in last week’s showdown. Facing a feisty Tim Kaine, whose debate appearance will likely be remembered for his aggressive interruptions, Pence was calm and refused to be baited.

But defending the polarizing GOP nominee was an almost impossible assignment as Pence was forced to dodge questions and the trail of explosive rhetoric strewn by Trump over the last 18 months. The constant controversies have bolstered the Clinton campaign’s momentum and claims that the real estate magnate is simply not fit to serve as President of the United States.

“He is not a polished politician like you and Hillary Clinton,” Pence said, when Kaine challenged him to explain a controversial comment by Trump that women who get an abortion should be punished. (Trump later walked back that remark.)

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Pence said he was “happy” to defend Trump, but most often ignored Kaine’s assaults on the GOP nominee, denied some of his running mate’s most controversial quotes, or sought to turn the attack back against Clinton over vulnerabilities like her private email server and record as secretary of state.

Road test for next debate

The clash at Longwood University in Farmville, Virginia, allowed both campaigns to road test fresh attacks that Clinton and Trump can use during the second presidential debate on Sunday, which will be co-moderated by CNN’s Anderson Cooper. It served as a possible reset moment for both campaigns after a week dominated by a series of troubles for Trump following his underwhelming debate performance last week and a stunning New York Times report over the weekend that a loss of more than $900 million could have resulted in him not paying taxes for 18 years.

It’s unclear whether Pence’s strong performance will rub off on Trump.

“The media is saying Pence won, but didn’t really defend Trump,” a senior Trump campaign aide said. “That isn’t setting well with the boss.”

Kaine, a Virginia senator, was aggressive and sometimes frenetic, a style that threatened to irritate viewers at times by interrupting his rival at the debate table. He repeatedly recalled Trump’s harsh rhetoric on women, Mexicans and African-Americans, and accused the Republican nominee of harboring admiration for hardline leaders such as Russian President Vladimir Putin and Kim Jong-un of North Korea who view the US as an enemy.

“Six times tonight, I have said to Gov. Pence, I can’t image how you can defend your running mate’s position on one issue or the next and on all six issues, he has refused to defend his running mate,” Kaine said. “And yet, he is asking everybody to vote for someone he cannot defend.”

GOP distances itself from Trump – again

Kaine came prepared with pre-packed zingers, branding Pence as Trump’s apprentice and asking millions of television viewers at home: “Do you want a you’re hired President with Hillary Clinton or do you want a you’re fired President with Donald Trump?”

The senator slammed Trump for speaking of Mexicans as rapists and criminals, to which Pence responded: “You whipped out that Mexican thing again.”

Pence wins

A CNN instant poll conducted after the event showed that 48% of viewers who watched the debate believed that Pence won and 42% thought Kaine was victorious.

The poll, however, does not represent the views of all Americans and samples only those who watched the debate. Its sample of debate-watchers broke down as 41% Democratic and 30% Republican, reflecting the make-up of the television audience.

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Pence may be scored the winner on style points, though his evasions on defending Trump could end up being more of a story in the days to come.

Pence’s solid performance may also have cheered Trump’s camp following the Republican nominee’s terrible week since his first debate with Clinton which has seen him veer off topic, feud with a former Miss Universe over her weight, bring up Bill Clinton 1990s sex scandals and defend his taxes.

Kaine’s performance, and the decision to repeatedly stress Trump’s liabilities and press the case for women’s and minority rights, may also have fired up Democratic base voters, as the Clinton campaign seeks to build late emerging enthusiasm for her campaign.

But vice presidential debates rarely change the course of presidential elections. And Tuesday’s clash will likely fade from memory within days in the build-up to Sunday’s crucial second presidential debate between Trump and Clinton. Only then will voters learn whether Trump can harness his emotions and volatile personality and build the kind of case against Clinton that Pence was able to construct on Tuesday.

Kaine’s strategy

Kaine’s strategy on Tuesday night – to brand Trump as an unacceptable choice for President – was clear from his opening answer when he said that for him and his wife, who have a son deployed overseas as a Marine, “the thought of Donald Trump as commander in chief scares us to death.”

He brought up Trump’s suggestions that nations like Japan, South Korea and Saudi Arabia should get nuclear weapons, which Pence denied his running mate had ever said. Pence also denied that he and Trump had both said that Putin was a better leader than Obama, though both clearly made that case.

Pence argued that if anyone is running an insult driven campaign, it’s Clinton. He said Trump’s comments were “small potatoes compared to Hillary Clinton calling half of Donald Trump’s supporters a basket full of deplorables.”

Pence made an effective assault on the Obama administration’s foreign policy, which he said had been orchestrated by Clinton, reflecting the underlying theme of the campaign — a contrast between continuity and change. He said after Clinton traveled the world as secretary of state, America was less safe than when Obama took office in 2009.

“It’s absolutely inarguable,” Pence said. “Mostly, it’s been a lack of leadership.”

But Kaine framed national security questions as a test of Trump’s character, which he said would be lacking as commander-in-chief.

“He trash talks the military,” Kaine said. “He wants to tear up alliances. …He loves dictators. Last and most dangerously, Donald Trump believes that the world will be safer if more nations have nuclear weapons.”

Clinton Foundation had filing issues, too

Pence mocked Kaine for what he said was a pre-cooked line.

“Did you work on that one a long time, because that had a lot of really creative lines in it?” Pence said, and branded the Clinton/Kaine campaign nothing but an “avalanche of insults.”

In an apparent departure from Trump’s stated policy on Syria, Pence said the US should be open to military action against Syrian targets of the regime of President Bashar al-Assad if what he called Russian provocations – namely attacks on civilians in besieged rebel-held areas of the city of Aleppo – continue.

“I just have to tell you that the provocations by Russia need to be met with American strength, and if Russia chooses to be involved and continue, I should say to be involved in this barbaric attack on civilians in Aleppo, the United States of America should be prepared to use military force to strike military targets of the Assad regime to prevent them from this humanitarian crisis that is taking place in Aleppo,” Pence said.

He also called for the setting up of safe zones for civilians in Syria – an idea that has been considered by the US government – and also backed by Clinton, But it has been judged impractical given the military complications it could entail – including direct confrontations between US and Russian military aircraft over Syria.

Pence also struggled to effectively defend Trump over the tax issues raised by the New York Times report about Trump’s mammoth tax write off.

“He actually built a business. Those tax returns showed he faced some pretty tough times 20 years ago,” Pence said, adding that the tax code was designed to allow businessmen like Trump to come back after taking risks.

CNN’s John King contributed to this report