Buck, a Tea Party favorite, is seen by some as a gaffe-prone sound-bite machine. He was blasted by his critics for saying that people should vote for him because, "I do not wear high heels."
"It's not easy to love a candidate that has a cowboy boot in his mouth," Buck joked at the time.
How Buck fares in November will present a test for the Tea Party supporters, which helped build Buck's grassroots momentum.
In the Colorado governor's race, the real tests will come in November. Former Republican Rep. Tom Tancredo, a firebrand in the anti-illegal immigration movement, left his party to join the small-time American Constitution Party.
Should he stay in the race, his presence could give aid to Democrats, especially with the deeply flawed Republican candidate Scott McInnis, who has been accused of plagiarism, also running.
In the race for the Republican Senate nomination in Connecticut, McMahon, who spent nearly $25 million of her own money on the primary, was well ahead of former Rep. Rob Simmons and Peter Schiff.
McMahon's decisive win came despite efforts by Simmons and Democrats to exploit her time as a WWE executive. They circulated clips of her in the wrestling ring and taking part in wrestling storylines that didn't sit well with women's groups or the family-values set.
McMahon today defended WWE's record and its programming that has increasingly gotten more risque and violent in recent years.
"It is an industry that's evolved and it will continue to evolve," McMahon said on GMA, adding that with any company when one looks back, "there were things that I would've done differently. What is important is, I think, where we are today and where we will be tomorrow."
In recent weeks, women's groups condemned some video clips of McMahon and her husband doing their day job at WWE, talking smack and getting smacked by her daughter. Connecticut Democrats compiled the most interesting videos in a playlist distributed widely.
After her victory, McMahon tried to move beyond the controversy, saying her election in November would help children.
"This election is about jobs," she said in a prepared statement. "The American Dream is threatened, but Washington continues its reckless spending, massive debt and tax increases. Washington is suffocating small businesses and killing jobs. This is not only threatening our well-being, but also the well-being of our children and grandchildren."
Democrats tried to spin McMahon's failure to crack 50 percent as a failure, given the vast resources she poured into the campaign.
Simmons, her closest rival, shuttered his campaign for more than a month before a last-ditch effort to revive it before primary day.
Democrats also made clear that the WWE theme will be front and center through November.
"Connecticut Republicans today nominated a corporate CEO of WWE, who, under her watch, violence was peddled to kids, steroid abuse was rampant, yet she made her millions," Sen. Bob Menendez, D-N.J., Democratic Senate Campaign Committee chairman, said after McMahon's victory.
McMahon dismissed Democrats' criticism.