Miami-Dade Commissioner Bruno Barreiro voted to award a $25 million contract to Munilla Construction Management to build a test track for Metrorail cars in May and again in November. In between both votes, he rented office space from the firm’s owners, county records show.

Less than two months before the second vote, four Munilla family members — Pedro, Juan, Jorge and Fernando — contributed the maximum amount of $500 each to Barreiro, who was well on his way to retaining his commission seat for a fifth time.

County records show Barreiro rented the office as his campaign headquarters between June and November, paying $700 a month for the property at 1429 SW First St., in Miami.

Barreiro, who acknowledges being close friends with several of the Munilla family members, has voted to grant at least two other multi-million dollar construction contracts to MCM in the past two years.

In late 2011, MCM won a $50 million contract to do miscellaneous work at Miami International Airport. Barreiro, as the chairman of the Regional Transportation Committee, sponsored the bill. In January, he voted to award a $7.7 million contract to the firm to expand Terminal D at PortMiami.

The commissioner said he did not perceive any conflict in renting office space from the Munilla family.

“If I got it free, it would be a conflict. I specifically made sure I paid rent,” said Barreiro, who did not seek advice from the county’s Commission on Ethics & Public Trust.

That agency’s guidelines prohibit elected officials from entering into contracts with persons or entities that do business with the municipality the elected official represents, “unless the transaction is an arms-length transaction made in the ordinary course of business.”

The issue came to light this week as part of a contentious bid protest in the city of Miami. The city’s procurement office is investigating whether MCM was operating out of the Southwest First Street office space when it bid on a multi-million dollar city contract this summer — or if the company was using the address as a phony satellite office to get preferential treatment in the procurement process.

Businesses that operate within city limits are favored over other contractors.

Miami first solicited proposals from companies interested in building a promenade at Museum Park in late July. Five companies responded, including the Chicago-based FHP Tectonics Corp., which offered the best deal: $7.7 million.

MCM offered to do the job for $8.4 million. But because MCM claimed to have an office operating within Miami city limits, and was offering a price close to FHP’s, both firms were given the opportunity to resubmit their bids.

After revising their pitches, MCM proffered the better value: $7.62 million compared to FHP’s new offer of $7.64 million.

In early October, the city’s Capital Improvements Department recommended the city choose MCM.

But questions soon began to surface about the Miami address MCM had given the city procurement office. FHP officials drove by the Southwest First Street property on at least three occasions and found only Barreiro’s campaign office, according to affidavits provided to the procurement office.

“On the sign was the picture and name of Bruno Barreiro,” Todd DeCarolis of FHP wrote in a sworn statement. “I went in the front door to confirm and there was one older, Spanish gentleman and when I asked for MCM, he replied, ‘Not here.’ ”