BOSTON -- Sen. John McCain's soon-to-be-announced running mate will learn of their fate Thursday, prompting Republicans in Massachusetts to prepare.

McCain's headquarters in Boston opened on Wednesday. NewsCenter 5's Sean Kelly reported that Republicans showed strength inside their new office while supporters of Sen. Barack Obama, D-Ill., outnumbered the Republicans across the street.

McCain supporters then gathered outside to face the Democratic loyalists who gathered on the street.

"If anyone can do it here in Massachusetts, it's going to be John McCain," said Holliston Rep. Paul Loscocco, R-District 8.

Local McCain supporters who countered the Democrats who gathered on the street avoided direct attacks on Obama, leaving that to their candidate, who released a new ad on Wednesday called "tiny." The ad claims the Obama is "dangerously unprepared" for the White House.

McCain has enjoyed broad support in Massachusetts since 2000. Republicans believe they've held those voters and can land conservative Democrats.

"We have them and we're reaching out getting more and more people," state Republican Chairwoman Jean Inman said. "We're ready right now to do that."

Former Gov. Mitt Romney, rumored to be on McCain's "short-list" of possible running mates, remained mum on the vice presidential issue Wednesday.

Romney Mum On GOP Veepstakes

"Nothing on the (vice presidential) front for you guys," Romney said.

At McCain's Boston headquarters, there was no politicking yet to name Romney as running mate, but his fellow Republican -- former Gov. Paul Cellucci -- said he believes Romney would be a strategic pick.

"I don't think there's any downside," Cellucci said. "He's a hard worker with a spotless reputation. He's smart on the economy and he might deliver Michigan."

"I was very moved by Sen. (Edward) Kennedy and by his effort to come here, and by his remarks. It was a powerful thing to do and a class act. He's quite a guy," said Romney, who is in Denver and was asked about the Democratic National Convention so far.

When asked why he was in Denver, Romney said to make sure "they talk about the issues, and not just celebrity."

Republicans are preparing for their convention in St. Paul, Minn., next week.