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.

Deval Patrick, asterisk.

The Bay State’s first black governor, and the first Democrat to win the corner office in 16 years, is at risk of turning into a blip in Massachusetts political history – a one-term governor whose legacy becomes the zeal to replace him with a Republican.

In the early voting – money – Republican Charlie Baker is winning.

Baker raised $1.85 million over five months of campaigning, giving him three times more cash on hand than Patrick. That’s a fairly serious wake-up call for an incumbent Democrat who is best friends with a president.

Some of Baker’s money is coming from traditional Democratic donors, including previous Patrick supporters.

Baker’s big bucks mean one thing to Lawrence DiCara, a longtime Democrat. “He’s for real, which I knew anyway,’’ said DiCara, who remains a Patrick supporter.

Still, it’s only Round One. It’s a winning one for Baker, the former CEO of Harvard Pilgrim Health Care, but there’s a long way to go before a knock-out. One question, said Democrat Scott Harshbarger, a former attorney general and gubernatorial candidate, is whether this is “one-shot money’’ – contributions from people who know Baker, like him and owe him what Harshbarger labels “the chits of good will’’ – or something deeper and more dangerous for Patrick.

Baker was “able to translate his reputation and record into a significant fundraising event. If the next round demonstrates significant political strength . . . don’t kid yourself, this is going to be a major fight,’’ Harshbarger said.

Rob Gray, Baker’s chief strategist, predicts the money flow to the Republican’s campaign is “eminently sustainable.’’ He attributes the fundraising success to “a combination of people knowing Charlie as a government leader and a business leader and believing in his ability . . . plus a dissatisfaction with the way Deval Patrick has managed, or really not managed effectively, the state budget.’’

The landscape is tough for Democrats nationwide, from the president to members of Congress to governors. Voters are angry over fallout from the poor economy and unhappy over some policies, such as healthcare reform.

In Massachusetts, disappointment over Patrick’s tenure is translating into a real sense of political vulnerability. He was elected with expectations so high they would be difficult to meet under the best circumstances. A poor economy, plus Patrick’s own missteps, worsened the gap between promise and reality.

He was once a key member of Deval Patrick’s team – the communications director in the early months of the 2006 campaign. But now Kahlil Byrd, who also served as Patrick’s appointments secretary once Patrick won office, has broken with the governor. He has become a devotee of Charles D. Baker, the Republican former health care executive looking to unseat the man Byrd once called boss.

“The governor’s a great man in the wrong job,’’ said Byrd, who now works as a senior fellow at a Washington think tank and runs his own strategy firm. “The governor could have led us through tough times by tapping into the spirit of innovation that is much of a part of Massachusetts. He hasn’t succeeded, and unfortunately he’s lost the promise of his 2006 campaign.’’

Byrd is a Republican. He worked for longshot GOP candidate Jeff Beatty in his bid to unseat Senator John F. Kerry in 2008.

Byrd gave the maximum allowable amount, $500, to Baker’s campaign in 2009. He said he was drawn to Baker because he’s been “deeply involved in public policy and government in Massachusetts for a long time’’ and has also been “a successful leader in the private sector. He’s excited about becoming governor when our problems are at their deepest.’’

Gov. Deval Patrick’s punchy campaign staff sent out an e-mail blast to supporters Monday night hoping to blunt yesterday’s Herald expose on the administration’s year-long hiring frenzy, flinching even before the brutal news hit the street.

But experts warn the attempted pre-emptive political strike is risky business for the slumping governor’s re-election bid.

“It just whiffs of desperation,” said Thomas Whalen, a Boston University political science professor. “It sounds like they can’t afford to have any bad news, so they’re trying to get on top of bad stories before they even come out.”

Patrick campaign officials sounded the alarm Monday night – hours before the Herald’s splash landed on racks. The report detailed how the administration has hired some 1,300 new employees this year – including a librarian for cons, a painter for public health and a “game biologist” – despite a spiraling fiscal crisis.

“The story may unfairly distort the Governor’s outstanding record of confronting our state’s budget challenges,” Patrick campaign manager Sydney Asbury wrote in the e-mail obtained by the Herald.

Asbury also urged readers to “forward the e-mail to 10 friends” in an attempted viral campaign to spin the story in their favor.

However, a subsequent Herald payroll analysis shows the administration in fact low-balled the projected annual salaries of some of the new hires by as much as $34,000.

Reached yesterday to explain the mistaken figures provided to the Herald, Sally McNeely of the state Human Resources Division, said, “It appears an error was made in the initial entry.”

Meanwhile, Patrick campaign spokesman Steve Crawford said the e-mail blast – which highlighted a 2,000-job net loss from the state payroll – was standard operating procedure. “We place a high level of importance on keeping our supporters informed and this is another example of that,” he said.

A rapid response to head off bad press isn’t new to political campaigning, but it runs the risk of spreading negative news to an even larger group, said Larry Sabato, a University of Virginia political science professor.

“It can end up drawing even more attention to the matter,” said Sabato. “Obviously Patrick has a very tough general election in front of him, and he has to come out swinging every time there’s a charge against him.”

Diane Patrick, the governor’s wife, issued an impassioned plea yesterday to elect US Representative Michael E. Capuano to the US Senate, but the congressman hedged when asked whether her support might help him against Attorney General Martha Coakley, the perceived front-runner and sole woman candidate.

“It’s more personal than anything else to me,’’ Capuano said of the endorsement. “I’ve said from day one, I’m not concerned about gender issues.’’

Although Governor Deval Patrick remains officially neutral in the four-way Democratic primary race, his wife called Capuano a “tenacious fighter’’ who would make a difference on the Senate floor.

“Mike is, number one, a brilliant strategist, and I don’t mean that in the sense of campaigning, but in the sense of getting the job done,’’ Patrick said at a campaign stop before about 150 people at the Dedham Community Theater. “What you see in Mike Capuano is what you get. He is the most genuine man I know.’’

The primary election, to be held Dec. 8, also includes political newcomers Stephen G. Pagliuca and Alan Khazei.

The endorsement by Diane Patrick, a law partner at Ropes & Gray, follows similar public support for Capuano from US House Speaker Nancy Pelosi and Kitty Dukakis, the wife of former Massachusetts governor Michael S. Dukakis.

Capuano said he is “proud’’ to receive Patrick’s backing, which follows the congressman’s early support for her husband’s gubernatorial campaign. But when asked to rate its importance, Capuano replied, “I have no idea.’’