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NBC News has learned from two knowledgeable Democratic sources that Hillary Clinton intends to announce her choice of running mate Friday evening by text message to her supporters.

Her first joint appearance with her newly minted running mate is slated to be Saturday at a rally in Miami.

Clinton originally appeared ready to announce the identity of her choice at a rally in Tampa, Florida, but that timetable appeared to slip.

On Friday evening, campaign chairman John Podesta was calling candidates not chosen for the job.

Monitoring the horrific situation in Munich. We stand with our friends in Germany as they work to bring those responsible to justice. -H — Hillary Clinton (@HillaryClinton) July 22, 2016

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Clinton's Brooklyn staff expected to be told of the pick during a meeting this afternoon. Instead campaign manager Robby Mook opened the meeting by saying they will have to wait until “an undisclosed time” for the news, per a source in the meeting.

Virginia Sen. Tim Kaine remains the overwhelming favorite among insiders, but sources caution that Agriculture Sec. Tom Vilsack is also a top contender. The next most talked about names includes New Jersey Sen. Cory Booker and Labor Sec. Tom Perez.

Kaine arrived in Boston Friday morning for a previously scheduled fundraiser, telling NECN he was "looking forward" to the fundraising event.

But asked if he has spoken to Hillary Clinton, Kaine demurred.

“That’s all I’m going to say," he said.

The Clinton campaign was considering at least two options for the VP rollout. One potential plan called for unveiling the pick 24 hours earlier and making a joint appearance at the Friday evening rally in Tampa. But seeing the negative press coverage surrounding Donald Trump’s Republican National Convention, Democrats were not eager to change the topic of political conversation and happy to let Trump stew an extra day of bad press, Democrats close to the process said.

Kaine, a former governor and Democratic National Committee chairman, has long been the frontrunner, checking almost all the boxes sought in a running mate.

He was a finalist for the position in 2008, but Barack Obama instead chose Joe Biden, the then-chairman of the Senate foreign relations committee, citing his national security credentials.

When Kaine entered the Senate in 2013, he joined both the Senate Armed Services and Foreign Relations Committee. He has traveled to at least 23 foreign countries on official business, including hotspots like Afghanistan, Iraq, Pakistan, and Israel.

In addition, Kaine is a popular politician from a key swing state and speaks fluent Spanish, a skill he would likely demonstrate in Miami if selected. He also attends a black a church and was elected mayor of majority African-American Richmond, Virginia.

Clinton’s campaign is hoping to use their tightly run vice presidential selection process, and next week’s Democratic National Convention, to contrast with Donald Trump’s messier process.