'Nightline' Daily Line, July 18: Romney Still Undecided on VP Pick, Wife Says

5:16 p.m. ET: "Nightline" anchor Terry Moran tweets:

Credit: Kizzy Cox/ABC

Get a taste of what's to come in Terry's interview HERE

4:33 p.m. ET: ABC NEWS EXCLUSIVE: Sen. Marco Rubio today got the nod to be the 2012 Republican vice presidential nominee - from the nation's largest Tea Party group, not Mitt Romney.

"It is not a big surprise that Marco Rubio is the favorite candidate of the tea party for the vice-presidential nod. He ran as a strong fiscal conservative, and he has delivered with his record in the U.S. Senate for the last two years," said the group's president Amy Kremer in a statement. "The only surprise is that he led the other excellent candidates by such a wide margin."

Read the full story HERE and watch the video here:

3:01 p.m. ET: "Are you real, Mona Lisa?" - Nat King Cole

The bones of Mona Lisa, the woman who posed for Leonardo da Vinci's famous masterpiece in the 1500s, may be located beneath an altar in an Italian church, according to researchers.

Read the full story HERE

Credit: Claudio Giovannini/AFP/Getty Images

1:28 p.m. ET: Happy 94th birthday, Nelson Mandela!

Family members wishing Nelson Mandela a happy birthday at his home in Qunu, Eastern Cape, South Africa. Credit: Peter Morey

11:48 a.m. ET: Mitt Romney is still undecided about his choice for vice president, according to his wife, Ann Romney.

"We're not quite there yet," Ann Romney told ABC's Robin Roberts of her husband's thinking in an exclusive interview to air Thursday on "Good Morning America."

Read the story HERE.

Credit: Ida Mae Astute/ABC

10:50 a.m. ET: DEVELOPING: A suicide bomber at Syria's national security building has killed the country's defense minister and the Syrian president's brother-in-law, and wounded other senior officials, Syrian state-run TV said.

Read the full story HERE

AP Photo; AFP/Newscom

9:37 a.m. ET: Give praise to "The Dark Knight Rises," or else.

The movie-review aggregation site RottonTomatoes.com announced that for the first time ever they are suspending user comments after some movie critics who gave negative reviews to "The Dark Knight Rises" were receiving vile backlash.

Read the full story HERE

"Nightline" was granted an exclusive interview with director Christopher Nolan, who talked about why he has decided to end his blockbuster "Batman" trilogy:

And why he chose Bane as his villain: