Possible Harris VP picks are unknown to most Americans, according to Josh Shapiro and Tim Walz.

Governor who? Senator what's-his-name?

The three leading candidates for Vice President Harris' running mate on the Democratic presidential ticket are Arizona Sen. Mark Kelly, Pennsylvania Gov. Josh Shapiro, and Minnesota Gov. Tim Walz. However, a majority of Americans are unfamiliar with these potential vice presidential candidates, according to an NPR/PBS News Marist poll.

Kelly is the most popular candidate for the No. 2 job in the White House, with 31% of respondents finding him favorable and 18% unfavorable, but 52% of respondents are still unsure or have never heard of him.

Since Harris will make her first appearance with her running mate in Philadelphia, Shapiro, who is speculated to be the front-runner in the veepstakes, has a 25%-23% favorable to unfavorable rating. However, 53% of Americans are unsure.

Of the three candidates, Walz is the least well-known among progressives, with 71% of survey respondents admitting they were unfamiliar with him.

In the latest Marist survey, Harris's favorability numbers have increased from 40-44% to 46-48% favorable-unfavorable.

The GOP candidate, former President Trump, is viewed mostly unfavorably, 53%, by respondents, while 44% have a positive view of him. Trump's unfavorable score increased four points since the last Marist poll, which was taken after the Republican National Convention and the assassination attempt on his life in Butler, Pennsylvania.

The survey of 1,613 adults was conducted between Thursday and Sunday and has a margin of error of +/- 3.3 percentage points. Respondents were contacted through cellphones, landlines, or online research panels in both English and Spanish.

On Tuesday evening, a rally in Philadelphia will see Harris reveal her choice.

As the presumptive Democratic nominee for president, Harris will make her first visit to Pennsylvania on Monday. This trip will be her seventh visit to the commonwealth this year and her 17th since she was sworn in as vice president in 2021.

After President Biden dropped out of the 2024 race and endorsed Harris to succeed him, Kelly, Shapiro, and Walz are the finalists for the VP job in a truncated vetting process.

Harris held in-person interviews with potential running mates in Washington, D.C. over the weekend, according to Democratic sources. Among those being considered are Govs. Beshear and Pritzker, as well as Transportation Secretary Buttigieg.

Before her interviews with the candidates, Harris received a briefing from a vetting team headed by former Attorney General Eric Holder.

The announcement of the rollout is uncertain, but it may be made through a video introduction, like how Biden announced Harris as his running mate four years ago. However, the Harris campaign's plans could be disrupted on Monday or Tuesday by a media leak of the announcement.

Harris and her running mate will embark on a comprehensive swing state tour through Pennsylvania, Wisconsin, Michigan, North Carolina, Georgia, Arizona, and Nevada, the seven battlegrounds that will most likely decide the presidential election's outcome, following the rally in Philadelphia.

Last week, at the Georgia State Convocation Center in Atlanta, the vice president attracted over 10,000 attendees to her first significant rally since assuming the role of Democratic ticket leader, replacing Biden.

JD Vance, the Republican candidate for vice president, will shadow Ohio Senator Kamala Harris on her tour, according to Planet Chronicle. Harris will act as the Trump campaign's attack dog, trying to convince voters not to support her in crucial swing states.

Planet Chronicle Digital's Paul Steinhauser and Landon Mion contributed to this report.