Democratic and Republican convention planners are in a race, not to nominate the best presidential candidate but to be greener and cleaner than the competition.

Officials in both host cities -- Denver, Colo., for Democrats and St. Paul., Minn., for Republicans -- are busy making sure their conventions are as energy-efficient as possible, powered by alternative fuel sources and full of ways for guests to be environmentally conscious.

In Denver, Democrats say when they make their mark on history later this month, they don't want to leave a big footprint.

"Denver has been a city for so long that has prided itself on being sustainable and becoming green that we said from the beginning we would have the greenest convention," Denver Mayor John Hickenlooper said.

Planners and so-called greening directors say the goal is to have the most environmentally friendly convention ever.

"The whole thing about green that's very different now than it was even a few years ago is it is not something that happens at the end of the day, it's something that gets designed into what you do," said Parry Burnap, Denver's director of greening.

The Democrats' venue, the Pepsi Center, will be powered in part by wind and solar energy.

They will have 1,000 bikes on hand as well as hybrid buses for visitors. Delegates will get reusable water bottles -- they even booked hotels online to save paper.

In a city whose mayor wears a pedometer, there is a sense of rivalry about being the greenest.

"You know, Denver already is greener than Minneapolis-St. Paul, so I think it's likely that we will have the greener convention," Hickenlooper said.

Not if St. Paul planners have anything to say about it.

Republicans officials are taking similar measures. Convention staff and delegates will be driven around in hybrid and flex-fuel vehicles when they meet the following week. Or they can bike, for free, using the 1,000 donated bicycles.

And the Xcel Energy Center, where the convention is being held, also will be powered by alternative sources of energy.

"Every light and microphone that's gonna be turned on at the convention center's gonna be powered by either wind or solar energy," said David Sparby of Xcel Energy.

And the plan is for everything from carpeting to used furniture to plates and cups to be recycled locally.

"We are energy efficient -- with regards to our office, with regard to electric strips, where we can turn things off and not lose power," Republican convention CEO Maria Cino said.

In an election year when energy concerns dominate debate, planners are hoping to send the message that, according to Cino, "we care about this issue and getting our folks motivated to not only be green but also get out and vote."

FOX News' Alicia Acuna and Steve Brown contributed to this report.