Narrowly staving off a potential primary from a Tea Party challenger, Republican candidate for governor Charlie Baker won a resounding endorsement from his party on Saturday, promising to improve education, partner with cities and towns, and expand business opportunities.

Narrowly staving off a potential primary from a Tea Party challenger, Republican candidate for governor Charlie Baker won a resounding endorsement from his party on Saturday, promising to improve education, partner with cities and towns, and expand business opportunities.

Baker, who four years ago was felled by Gov. Deval Patrick’s re-election campaign, was back on the stage at his party’s convention, accepting the overwhelming endorsement from the more than 2,500 delegates who traveled to Boston University’s Agganis Arena.

Only a razor thin margin separated Mark Fisher, a Tea Party Republican from Shrewsbury, from qualifying for the ballot to challenge Baker for the Republican nomination in September, a possibility the Baker camp strove to avoid and which would have prevented party financial resources from flowing to either candidate until after the primary.

The ballot counting lasted hours after the convention adjourned as Fisher challenged some of the ballots.

Fisher fell just short of the 15 percent of delegates he would have needed to qualify, according to party officials, capturing 14.7 percent of the 2,533 delegates present.

“Primary or no primary, we’re chasing 100 percent of the vote in November,” Baker said.

Baker and his running mate Karyn Polito, a former state representative who is also from Shrewsbury, emerged from the rather staid affair with the strong backing of the Republican Party as both offered themselves up as an alternative to the one-party rule on Beacon Hill and eight years of Gov. Patrick. Recent troubles with the Department of Children and Families, the health exchange website, medical marijuana licensing and other issues provided ample fodder for Republicans throughout the day.

For Baker, 2014 is his chance at redemption after losing in 2010 and feeling like he didn’t put his best foot forward during that campaign. Baker hosted a women’s breakfast early in the morning with Polito and his wife Lauren, interacting with a constituency that he failed to galvanize during his last run in 2010.

“I’ve been successful because I am an optimist. I believe in this great state and I believe it’s ready to soar but we aren’t going anywhere if the powers on Beacon Hill protect the status quo,” Baker said.

Baker promised to fix the dysfunctional Affordable Care Act's health insurance exchange that has become an embarrassment for the Patrick administration, improve the business climate and tackle the educational achievement gap facing low-income and minority students. He also hit Patrick and Democrats for troubles at the Department of Children and Families, property taxes “run amok,” and a gas tax indexed to inflation that opponents are trying to repeal in November.

“This is the problem with one-party rule. There’s no accountability. No price to be paid for getting stale. No pushback. No urgency. No debate. Just the giant muddle of the status quo,” Baker said. "This isn’t good enough for Massachusetts. Not your Massachusetts. Not mine. We can and must do better.”

Baker gave his acceptance speech to a considerably emptied arena. Many delegates left after casting their votes. The convention adjourned hours past its scheduled end time, and many who did remain were buzzing instead over whether Fisher had qualified for the ballot.

Fisher offered a far different message than Baker, eschewing the idea that the Republican Party should be a “Big Tent” party more accepting of differing viewpoints. He said the party establishment has become too “liberal.”

“Big Tents are for circuses and the Democrats have enough clowns parading as politicians to fill the biggest tent,” Fisher said, promising to crack down on illegal immigration and fight for smaller government and against tax increases.

Though the party endorsement heading into the convention was never in doubt, Baker faced the challenge of trying to appeal to and appease the more conservative party activists who were gravitating toward Fisher. With his former running mate Richard Tisei, who is running for Congress, boycotting the convention over the GOP platform on gay marriage, Baker steered clear of social issues.

“I know some of you here today don’t agree with me here on everything and I get that and I respect that. I believe in the big tent of the Republican Party,” he said.

Fisher pointed out that he is the only gubernatorial candidate who has taken a no-new-taxes pledge, but Baker also addressed taxes.

“We need to get over this notion that state government’s problem is revenue,” said Baker. “State government doesn’t lack resources. It lacks imagination. There are faster, better, cheaper ways to get things done. And they must be identified and pursued.”

Polito was nominated by Republican Governors Councilor Jennie Cassie and Rep. Viriato deMacedo, a Plymouth Republican running to take the seat held by retiring Senate President Therese Murray. DeMacedo was greeted with chants of “Vinny, Vinny!”

“We deserve a state government that reflects the conversations happening at our kitchen tables at home, a government that balances its checkbook, lives within its means and saves for the future,” Polito said.

Polito also faulted the Patrick administration for the state’s 6.5 percent unemployment rate, and the ongoing controversy regarding the disappearance of a 5-year-old Fitchburg boy under state’s watch.

“May we never again see the day when an innocent child is lost in the care of our state, Polito said.

The convention also offered an opportunity for the party to showcase its candidates for other statewide offices, including treasurer, auditor, attorney general, secretary of state and U.S. Senate.

Patricia Saint Aubin, a Norfolk state committeewoman and the Republican nominee for auditor, picked up where 2010 nominee Mary Connaughton left off during the last election cycle when she narrowly lost to Auditor Suzanne Bump.

Just as Connaughton contrasted her professional experience with Bump’s, Saint Aubin said, “I have a dirty little secret, and that is I have a bachelors in accounting from Providence College.”

Treasurer candidate Mike Heffernan discussed his desire to boost local aid by running an efficient Lottery and pay down the state’s long-term pension liability, while David D’Arcangelo said he would fight for greater transparency on Beacon Hill.

John Miller also became the GOP nominee for attorney general, while Brian Herr received the endorsement to take on U.S. Sen. Edward Markey.

National Republican Committeeman Ron Kaufman said Baker was not afraid of a primary but would benefit from avoiding a challenge because Massachusetts campaign finance laws make it harder for Republicans, who make up the minority of the electorate, to compete.

“It’s preferable for one reason. We have the worst campaign finance laws in the country,” Kaufman said, pointing to a $500 contribution limit coupled with the fact that primaries are late in the cycle and candidates cannot solicit maximum contributions for both the primary and the general as they can in other parts of the country.

Rep. Matthew Beaton, a Shrewsbury Republican who seconded Baker’s nomination, said, “We must leave here united, ready to hit the ground running.”

Though the prevailing sentiment was that Baker would be better served by avoiding a primary, some wanted to see the contest.

Jim Morose, a Danvers delegate who planned to vote for Fisher, said voters deserved a primary, which the Republican Party has often sought to avoid, in order to air and debate different ideas.

“I just like competition. Whatever we’ve been doing for the past 20 years hasn’t been working, so why not try something different,” Morose said.

Morose said he would support Baker if he became the nominee, arguing that Baker would bring fiscal restraint to Beacon Hill.

A smaller sample of Republicans said they would have trouble supporting Baker moving forward because of his positions on abortion and gay marriage.

“I’d be sad if there isn’t a primary. I can’t support Baker,” said Debbie Frame, a Warren Republican.

Steve Aylward, a state committeeman who came to the convention uncommitted, said he was looking for either Baker or Fisher to show that they would fight the Democrats.

“I’m tired of our guys backing down,” said Aylward, who is behind the effort to repeal the gas tax indexing law at the ballot in November.

Attorney General Martha Coakley’s campaign manager Tim Foley sent out a fundraising email in the midst of the convention festivities: “Charlie Baker’s Republican party? They’re celebrating their conservative views on equality and women’s rights - views that would move our state backward.”

MassGOP Chairwoman Kirsten Hughes accused Democrats of avoiding talking about and taking responsibility for the scandals at the Department of Children and Families and the state crime lab.

“They’ve turned to their usual tactic, smoke and mirrors, creating policies that sound good to the average voter, but don’t amount to much. Their support for the minimum wage is a sad example, because it’s not going to lift anyone out of poverty. Raising the minimum wage is not a jobs plan. It’s political pandering,” Hughes said.