AMBLER, Pa. — Democrat Josh Shapiro had a dual message for enthusiastic voters in suburban Philadelphia this week, telling them Kamala Harris belongs in the White House — and then reminding them of all he’s done as governor of battleground Pennsylvania.

Kentucky Gov. Andy Beshear, likewise, told voters in Georgia that Harris has the makings of “a great president” — and then highlighted the elections he’s won as a Democrat in Republican territory.

The two governors were demonstrating a time-honored tradition in presidential campaigns: Summertime auditions from vice presidential contenders who walk the line between open self-promotion and loyal advocacy for the potential boss.

Vice President Harris, the likely Democratic nominee, appears intent on making a choice that she’s comfortable with personally and that can expand her electoral appeal in a matter of days. Her campaign has been vetting about a dozen potential running mates, according to people familiar with the search process. Shapiro and Arizona Sen. Mark Kelly are seen as among the front-runners, according to the people.

Three people familiar with the vice president’s plans said Tuesday that she and her yet-to-be-named running mate would begin traveling to battleground states next week — suggesting that a decision could be coming soon.

The people said they didn’t know who her pick would be or which states Harris could visit. They spoke on the condition of anonymity to discuss details that haven’t been made public.

In the meantime, Harris advisers, led by former Attorney General Eric Holder, have been combing through reams of paperwork submitted by potential running mates, while the candidate herself is holding personal conversations with the finalists, according to a person familiar with the matter.

Harris, according to another person familiar with the matter, is seeking someone with executive experience who can also serve as a governing partner. Notions of a so-called short list have not stopped those on the Democrats’ broader national bench from finding the spotlight.

“I’m not going to talk about the interactions I’ve had with the campaign,” Illinois Gov. J.B. Pritzker declared recently on MSNBC. He added, though: “Let’s just say I’m aware that the vetting process is quite an in depth one.”

Then he listed his accomplishments, offering that he was the only Midwestern governor to raise his state minimum wage to $15 per hour. Michigan Gov. Gretchen Whitmer, once held out as an ideal nominee if Biden bailed out, has said, more or less, that she’s not a contender. But she appeared Monday with Shapiro in Pennsylvania and mused on MSNBC last week that “two women on the ticket would be exciting.”

Harris would be the first woman, first Black woman and first person of South Asian descent to serve as president. Many Democrats have argued she should balance her ticket both demographically and politically.

Shapiro, 51, is among the most popular U.S. governors, winning his 2022 election in a rout over a Trump-endorsed Republican. He’s an outspoken supporter of abortion rights who has won three statewide elections in Pennsylvania. Beshear stands out in a heavily Republican state.

During his weekend stop in Georgia, he talked of winning votes in “tough counties” but emphasized liberal bona fides: “I am a proud pro-union governor. I am a proud pro-choice governor. I am a proud public education governor. I am a proud pro-diversity governor.