(CNN)Sen. Tim Kaine and Gov. Mike Pence come into Tuesday night's debate with a mission.
What to watch in the vice presidential debate
Pence needs to help Donald Trump recover from his lost week and re-focus his message, as well as convince people the White House is in good hands with the unpredictable Trump. Kaine wants ensure Hillary Clinton can solidify her post-debate gains in several swing states and in national polls.
Here are five things to watch when the vice presidential nominees sit down for their only debate:
On releasing tax returns, birtherism, debate prep and name-calling, Pence has chosen to go his own way during the campaign. He has also talked about his record in Indiana as a conservative governor. That daylight has left Trump in a somewhat awkward position and it's allowed Pence to maintain a future in politics.
But breaking with your opponent in a studio interview is one thing, doing it on stage next to an opponent who wants to pummel your running mate is something else entirely.
Pence has to defend Trump, who is boasting about "brilliantly" using tax laws for his benefit, after a New York Times story outlining a more than $900 million loss and suggesting he may not have paid federal income taxes for 18 years beginning in 1995. Look for Kaine to possibly exploit the fact that Pence has been transparent in releasing his taxes, compared to Trump who hasn't released them and is the nominee. And the Virginia senator will no doubt talk about Trump's temperament as commander-in-chief.
Pence will go on the attack against Clinton's policy record. Trump missed opportunities at the first debate to go after Clinton on obvious lines of attack like the Clinton Foundation and Benghazi. Pence, a former talk-show host, won't make the same mistake. "Hillary's record on foreign affairs alone could literally take up the entire 90 minutes and it wouldn't be pretty," he told supporters Monday night.
Donald Trump and his surrogates have spent the last week suggesting that this race will get nastier. Trump hinted that the next big debate topic would be the Clinton's marriage. He questioned Saturday night whether Clinton was loyal to her husband -- without offering any evidence that she isn't -- and mimicked her stumbling to a car when she was ill with pneumonia.
Meanwhile, Clinton and her surrogates have hammered Trump over comments he made about a former beauty pageant and for pushing birtherism.
Focusing too much on personality -- rather than substance -- could further turn off swing voters. But for Kaine, picking up the baton from Clinton, who had a successful performance, that could mean getting more distance in the polls. And for Pence, floating Clinton's marital troubles could lay the groundwork for Trump as a kind of trial balloon.
And also look for Kaine to highlight Pence's record on LGBT issues to paint the GOP ticket as out of step with swing voters. "I've been in elected life for 22 years, it's not knowing another fact, but it is about thinking hard about the material, thinking hard about Pence's record, and also what Pence's record would say about the guy who chose him, since it really is more about Donald Trump than it is about Gov. Pence," Kaine said about his approach to the debate.
Clinton and Trump both have record high unfavorability ratings: the latest CNN/ORC poll puts Clinton's at 54% and Trump's at 59%. Both VP candidates may try to sand off some of the rough edges and make people more open to backing their ticket.
Pence has argued that Trump is a decent and good man worthy of comparisons to Ronald Reagan. He has talked about quiet moments of prayer and reflection with Trump. And Kaine has vouched for Clinton's honesty and said that he can brag about Clinton in a way that Clinton can't brag about herself.
But it is one thing to say good things about their running mates, and it's another to show it. And this is where stories and anecdotes -- something this campaign has been short on -- can be helpful. Some of that was featured at the conventions this summer, with family members vouching for the candidates. For swing voters, who are sitting on the fence out of disgust with both candidates, humanizing and memorable portraits could be helpful.
In the first debate, Clinton introduced Alicia Machado, a beauty queen who Trump disparaged for gaining weight. She also got Trump to say it was "smart" that he possibly didn't pay federal income taxes. Both subjects have ended up in campaign ads and underscored Clinton's argument against Trump in new ways.
Pence and Kaine have the same opportunity. Trump failed to bring up Benghazi and the Clinton Foundation in his debate, and didn't break much new ground on the e-mail scandal either. A recent North Carolina poll shows that a majority of voters in that crucial swing state are bothered a lot by those issues. Clinton didn't talk much about Trump making his products out of the country.
So Pence and Kaine both have opportunities. The key is to cover old ground in new ways, either by using catchy phrasing (Clinton's "Trumped-up trickle down" was not so catchy), or by introducing actual new information. Clinton clearly had studied Trump's record. Pence and Kaine have a chance to frame an old issue in a new way, but it means hitting the briefing book and figuring out how and when to drop it in a debate. Both should study Clinton's playbook.
Alec Baldwin and Kate McKinnon have their hands full with Trump and Clinton. But surely there is room on the SNL stage for their running mates?
Yes, Kaine and Pence are boring by comparison. That is their purpose in this race, to soften their running mates. Pence says he isn't a name-caller. Kaine embraces his suburban dadness. They are standard issue politicians from the pre-Trump era. And perhaps that's where the funny is -- Kaine and Pence as a nice-and-nicer duo beleaguered by the foibles of their running mates. SNL's writing crew will be watching. Tuesday night could turn into a Saturday Night cold open. Casting tip: Bobby Moynihan as Kaine and Beck Bennett as Pence.
Or perhaps "Hamilton" creator and star Lin-Manuel Miranda, who is hosting.