Democratic Congresswoman Ann Kirkpatrick and Republican Sen. John McCain meet for the first and likely only time in a televised debate at 7 p.m. Monday on KAET-TV (Channel 8).

The 80-year-old McCain is seeking a sixth term in office; Kirkpatrick, who's served Arizona's First Congressional District for a combined three terms, would be the state's first Democratic U.S. senator in more than 20 years.

Here are three things to watch for at tonight's debate:

Kirkpatrick re-attaches McCain to Trump: Kirkpatrick wants to re-attach the current and former GOP presidential nominees, despite McCain's rejection of Trump on Saturday.

For a preview of what Kirkpatrick will try to do Monday night, check out this new TV ad the Kirkpatrick campaign will begin airing Tuesday morning. It not only dings McCain for supporting Trump over and over, but also revives his selection of Sarah Palin as running mate during his presidential run in 2008.

WATCH: Kirkpatrick's new TV ad links McCain to Palin, Trump

McCain makes Kirkpatrick relive her walkout: It came at a Holbrook supermarket in 2009, during the summer of protests over Obamacare. Kirkpatrick abruptly left a meeting with constituents upset over the Affordable Care Act. Obamacare now appears to be broken in Arizona. Residents in 14 of the state's 15 counties will have just one insurer to choose from next year on the Affordable Care Act exchange, and premiums are climbing.

The unexpected moment: Kirkpatrick's down more than 10 points in the polls. She needs something big to happen. McCain's abandonment of Trump isn't going over well with some Republicans. Here's what Republican National Committeeman Bruce Ash of Tucson told a reporter Monday:

Monday will be McCain's first public test drive without Trump -- he needs to handle that very carefully.