Engstrom said the group also has a strong grassroots network with 7.5 million activists across the country who will campaign on the chamber's behalf.
"This is intended to be a significant investment that is intended to move public opinion," said Engstrom. "You'll see an aggressive, continued approach all the way through November."
Matheson, who has voted with the chamber nearly 80 percent of the time during his 12-year tenure in Congress, said the group's endorsement speaks to his bi-partisan, pro-growth approach in Congress and distinguishes him from Mia Love, his Republican opponent in the race.
"This is an important validator and it's a wonderful contrast," he said. " I'm not about party. I'm about moving Utah forward and my opponent is all about party. So when someone wants to come to Utah for me who is from a nonpartisan organization that wants to grow our economy, I'll stand with them every time."
Matheson is one of just a handful of Democratic members of Congress that the chamber will endorse this cycle. Engstrom said the group endorsed 21 Democrats two years ago and the number will be smaller this year, although he couldn't say exactly how many there will be until all the endorsements are decided.
Love campaign spokesman Brian Somers said Matheson has hurt Utah businesses during his tenure in Congress.
"No endorsement can cover the fact that Jim Matheson has been a loyal foot soldier for the Obama administration, the most anti-business administration in generations," Somers said. "Matheson voted for the 2,300-page Dodd-Frank regulatory monstrosity, he voted for the crony capitalism embodied in the failed $800 billion stimulus, and he flip-flopped over and over on ObamaCare, which has increased labor costs and uncertainty for Utah businesses. The bottom line is that Utah businesses have suffered under Obama and Matheson's policies."
Love, was not considered for the group's nomination, Engstrom said, because Matheson met the chamber's threshold for the endorsement.
"If somebody is our friend and somebody meets our threshold … we're not going to run away from our friends," Engstrom said.
The group throws its support behind members who vote with the Chamber on at least 70 percent of the issues important to the group. Engstrom specifically cited Matheson's vote against the Affordable Care Act, for construction of the Keystone XL pipeline, for free trade and against further government regulation.
Matheson said he doesn't think those votes will cost him support among his Democratic base. "I think whether you are Democrat or Republican, you want to accommodate growth," he said.
Meanwhile, Love went on the air Tuesday with a 30-second spot touting her background.
Her campaign spent a little more than $51,000 on ads that will run until Aug. 27 on KSL ABC4 and Fox 13, according to filings with the Federal Communications Commission.
Similar reports show that Rep. Jim Matheson should be on the air on Oct. 15 through Election Day on Nov. 6 with a major campaign, which on ABC 4 alone will cost $84,000.
The buys were the first for the campaigns. Outside groups have already reserved more than $2.2 million in air time in the 4th District race.