The sound of dominoes falling...

The crushing momentum of state Sen. Scott Brown’s popular U.S. Senate campaign should be a wake-up call for Gov. Deval Patrick’s already shaky hold on the Corner Office , as Patrick’s three formidable challengers seek to cash in on a surge of voter discontent, said Beacon Hill observers.

“There’s no question that the Senate race significantly heightens the prospects of Deval Patrick’s challengers and it certainly only adds more to the worries that have already existed among Deval Patrick supporters,” said Paul Watanabe, political professor for the University of Massachusetts at Boston.

The gubernatorial race is expected to skyrocket into statewide prominence as voters energized by Brown’s come-from-behind race look for the next big candidate, said Democratic strategist Michael Shea.

“I think it’s a wake-up call to the governor and every Democrat in Massachusetts that there are lots of angry, frightened people out there, and they are striking out,” Shea said.

But state Democratic Party chairman John Walsh said the race also works in Patrick’s favor, because his Democratic base is now energized and unlikely to take any vote for granted.

“For Deval Patrick and Tim Murray, the implications are they need to talk to people on the ground and engage with them. Clearly that’s something they’ve been doing since they got there,” Walsh said.

State Treasurer Timothy Cahill, who is challenging Patrick as an independent candidate, said Brown’s unlikely bid has boosted his own chances.

“If anyone tells me over the next six months that I can’t win, I’ll look at them and say, ‘Did you say that about Scott Brown?’ ” Cahill said.

UPDATE: Please be sure to join us Wednesday night on The Notes on Blog Talk Radio! Our guest will be attorney and author Harvey Silverglate, the author of Three Felonies A Day: How the Feds Target the Innocent. Plus, more from Howie Carr and Michael Graham.

SECOND UPDATE: More from the Globe and AP.

THIRD UPDATE: More from the Globe, Herald and WBZ.