Clinton's new friend — and maybe VP

She starts the phone calls with, “Tom, this is Hillary.”
“Hey, how are you?” he responds, consciously working his way around being so formal at this point in their relationship, but also too ingrained in his Dominican upbringing to just start calling her by her first name.

Hillary Clinton and Tom Perez have had some practice with the routine, according to sources familiar with the conversations. There was the phone call when she called to ask for his endorsement, which became a nerd-out session on prison reform and registering farmworkers. In March, when she asked for his help on Latino engagement ahead of the New York primary, he pushed for her to send him to a politically powerful local union president to ask for his help — and ended up being asked himself to rile up a bundler session the morning after the New York debate.
Then there was the call in April, when she called to congratulate him about the new conflict of interest rule his Labor Department had just released. Before long, she was grilling him: who on the Hill had helped? What sort of response was he getting?
Perez had only met Clinton in passing before last summer, when he happened to get scheduled ahead of her at the National Association of Latino Elected Officials (NALEO) conference in St. Louis—just a typical day for a Labor secretary, he mock-complained to staff, with all those cameras arrayed to see him. She called over to him, introduced herself, thanked him for the work he was doing. They spent about 15 minutes together, complete with photos and teasing his former press secretary who’s now her director of black, Latino and women’s media.
But something clicked, between those encounters and the clutches he was pulled into before hitting the spin rooms at the debates he attended.
That’s how a low-profile Cabinet secretary who’s only ever been elected to the Montgomery, Md.,County Council ended up near the mix of Clinton’s running mate prospects. It’s largely a reflection of the relationship that he’s struck up over the past year with both the former secretary of state—who doesn’t make new friends easily—and former President Bill Clinton, and what they’ve seen him do.