Clinton offered a different outlook on the country than Donald Trump.
Clinton is expected to make the announcement Friday evening.
"I never thought I'd say these words," Clinton said.
“We stand with our friends in Germany," she tweeted.
"The rise of terrorism threatens the way of life for all civilized people."
The editorial board said it will not endorse Trump a day after he accepted the nomination.
Clinton has 41 percent support, with Trump at 38 percent among likely voters.
“All we saw was bitterness attacks and division,” she said.
Hillary Clinton is holding a rally in Tampa just as she's expected to announce her VP pick.
The Arizona Republican said Trump had a "good response" to "lock her up" chants.