Editor’s Note: This story has been updated to elaborate on the sources of money raised.

DENVER (KDVR) — Tuesday is the last day for Denver voters to cast their ballots in the runoff race, which will decide the city’s next mayor.

As part of the last week of campaigning, candidate Kelly Brough released a new ad highlighting political contributions her opponent Mike Johnston received from out-of-state billionaires.

Johnston is backed by the super PAC Advancing Denver, which has raised more than $4 million this election cycle. More than half that money comes from three wealthy donors: LinkedIn co-founder Reid Hoffman, former New York City Mayor Michael Bloomberg and former DaVita CEO Kent Thiry. Johnston responds to the criticism this week on “Colorado Point of View.”

At first, the Denver mayoral candidate highlighted other campaign contributions.

“We’re very proud of the fact that we have more than 3,000 donations from Denver voters. We have more small donations. We have the smallest average donation size … more total donations from people in the city,” Johnston said.

Election data shows nearly $6 million has been raised in support of Johnston, nearly doubling the amount raised to help Brough get elected. That money comes from direct campaign donations, the city’s fair election fund and donations to the super PACs that support each candidate. These super PACs can raise and spend unlimited amounts of money, including from corporations and unions, to campaign independently for candidates.

Johnston said his donors are not asking anything of him if he becomes elected, adding, “Nothing’s been promised.” But he alleged that’s not the case with his opponent’s donors: “70-90% are all developers or real estate interests with interests in front of the city. One corporate check of about half a million dollars from one corporate special interest. So I think that’s very different from our and our individuals who just care about good government.”

Watch the full interview with Mike Johnston on “Colorado Point of View” this Saturday at 7:30 p.m. on Channel 2.