WASHINGTON ­— Mitt Romney, in an effort to steer the conversation back to positive aspects of his business experience, wrote an opinion piece in Friday’s Wall Street Journal focused on his long tenure at Bain Capital.

The column, with the headline, “What I Learned at Bain Capital,” comes days before Republicans gather in Tampa to nominate Romney as their presidential candidate, a four-day event that is designed to promote Romney’s strengths.

His experience at the Boston-based Bain, a private equity company, has been the subject of harsh criticism, from Republicans during the primary race and from Democrats in recent months.

They have accused him of loading companies with debt and triggering bankruptcies while reaping millions of dollars for himself, his business partners, and their investors.

In his opinion piece, Romney highlights companies the firm helped start, including office-supply store Staples and child-care provider Bright Horizons,and struggling companies it helped get going again, such as retailer Brookstone and contact-lens maker Wesley Jessen.

“A broad message emerges from my Bain Capital days: A good idea is not enough for a business to succeed,” Romney wrote. “It requires a talented team, a good business plan, and capital to execute it.”

Romney details some of the ways he would use that philosophy and apply it to the federal government, as he did when he ran the 2002 Winter Olympics and when he served as governor of Massachusetts from 2003 to 2007.

Romney also said he would reduce the amount of government regulation.

“I’m not sure Bain Capital could have grown or turned around some of the companies we invested in had we faced today’s antibusiness environment,” he wrote.