Tim Kaine just warned Lester Holt and the media about holding Hillary Clinton and Donald Trump to different standards in Monday's debate. He didn't say those exact words, mind you. He actually didn't say the words "media," "Lester" or "Holt" at all. But look closely at the message he was sending — in that polite, Tim Kaine-y way.

Here's the Democratic vice-presidential nominee's exchange with Katie Couric in a Thursday interview:

COURIC: Do you think expectations are unfairly high for Hillary Clinton in this debate, compared to Donald Trump?

KAINE: I've worried about that. I've worried about it. ... Both candidates really ought to be challenged the same way.

Notice that Couric didn't specify whose expectations she was inquiring about. She could have been referring to — or, at least, including — the expectations of voters who will watch and use what they see to help make decisions in November. Yet Kaine clearly had the media in mind when he replied that "both candidates really ought to be challenged the same way."

The job of challenging the candidates Monday belongs to Holt, the moderator, and to the journalists covering the event, who will fact-check Clinton's and Trump's claims and evaluate their performances as meeting, exceeding or falling short of expectations. Kaine was telling Holt and the rest of the media not to grade Trump on a curve.

It's a big ask. Trump is still a rookie politician, while Clinton has been a first lady, a senator and a secretary of state. There are some legitimate reasons why it would be reasonable for journalists to expect Clinton to be more prepared for this moment.

What Kaine is probably most "worried" about, however, is the additional bar-lowering Trump has done by behaving so differently from previous major-party nominees. By hurling insults and cracking lewd jokes in the primary debates, Trump established a construct in which he can appear presidential, relatively speaking, simply by hewing closer to the norm.

If Trump does adopt a more dignified persona against Clinton, the media will surely take note. There is just no way around it. The best Kaine could hope for, in that scenario, is coverage that puts Trump's civilized comportment in context — noting his long record of reverting to coarser rhetoric and eyeing any new "pivot" with skepticism.