Against that backdrop, two genial and comparatively laid-back politicians, who share a deep religious faith that has shaped their careers, will meet onstage at Longwood University in Farmville, Virginia, for what will be their only face-to-face of the campaign. For many voters, it might be the first time they have heard from either man since the party conventions this summer. Here are some of the dynamics we'll be watching:

Pence and Kaine will not be the main focus at their own debate.

Don't let their physical presence onstage fool you: These two men may serve more as stand-ins for their running mates than as combatants in their own right.

In a conventional race, the vice-presidential candidates might engage in a thorough discussion of each other's records. But in a campaign defined by two larger-than-life presidential nominees, Kaine and Pence are more likely to punch upward, with Kaine prosecuting the case against Trump's temperament and character, and Pence pressing the message that Clinton cannot change Washington the way Trump can.

If it comes down to playing defense, Pence has the tougher task.

Pence can expect to be challenged on Trump's denigrating comments about Alicia Machado, a former Miss Universe; on his attacks on Clinton's marriage; and on the prospect that Trump may have gone nearly two decades without paying federal income taxes. And those are just the hits from last week.

Up to this point, Pence has proved adept at deflecting questions about Trump's incendiary comments, redirecting interviews to rote talking points about shaking up Washington. But a debate is an entirely different format; and as Sen. Marco Rubio of Florida found, using the same dodge over and over again can have catastrophic consequences.

How do Pence and Kaine see the vice presidency?

The vice presidency is one of the most prominent positions in politics, and one of the least defined. Presidents and vice presidents have enormous latitude to shape the role; the debate is the best chance Kaine and Pence have to set out their expectations for the job before one of them takes office.

The Democratic ticket in this race has been more clear in setting out a vision for the vice presidency: Clinton has said she chose Kaine to be a full partner in government, and he has talked about being a close counselor to Clinton if she is elected.

For Pence, there is more space left to fill in on the page. Trump said he selected the governor in large part to unify the Republican Party, but neither Republican has offered a clear vision for how Pence would function in government, an important question particularly given Trump's lack of experience in office.

The first presidential debate largely skirted social issues. Will this debate be a culture war?

In the first debate between Trump and Clinton, there was no discussion of abortion, contraception, gay rights or religious liberty — issues that define so much of American politics. In part, that's because Trump has never shown much enthusiasm for these issues; Pence and Kaine are different.

A Christian conservative, Pence is a longtime opponent of abortion and a champion of defunding Planned Parenthood; as governor, he signed and then scaled back an Indiana law that was widely criticized as opening the door to discrimination against gays and lesbians by private businesses. While Kaine, a liberal Catholic, has ample opportunities to brand Pence as too far right, he may also have to defend his strong opposition to the death penalty and mixed views on abortion.

Will the debate test the candidates' nice-guy images?

In a brutal political contest between candidates who hurl insults and point fingers, Pence and Kaine have tended to take a different approach. They've been forceful advocates of their ticket-mates, but both men have been likened to sitcom dads for their good humor and overall gentleness — especially, in Pence's case, in contrast to the Republican presidential nominee.

The debate on Tuesday will put those nice-guy images to their most strenuous test. It could potentially be a surreal viewing experience, after the rowdy first presidential debate, to see the records and credentials of Trump and Clinton picked over in a well-mannered conversation. But even nice guys hit their limits, and a nationally televised debate might represent just that moment for Pence or Kaine.