The fight over the marriage amendment intensified Monday when a star-studded group of opponents joined Minnesota political heavyweights for a chilly outdoor rally to energize the faithful and kick off their final push toward Election Day.

"We believe in an America that was founded on equal rights," Sen. Amy Klobuchar, D-Minn., told a roaring crowd of 1,800 outside the University of Minnesota's Northrop Auditorium. "We believe in an America that goes forward, not backward. ... So let's make good on the promise of America and defeat this amendment."

The event is part of a frenzied final effort by both campaigns to persuade voters on a measure that would change the state Constitution to define marriage as a union between a man and a woman. The other side, led by Minnesota for Marriage, is revving up its formidable campaign machine, including a surge of phone calling.

Both sides have much at stake in how they execute the final few days of a campaign that has been the most expensive and divisive ballot question in state history. A new Star Tribune Minnesota Poll shows the race deadlocked, so a flub could cost either side the race.

Monday's rally brought together swarms of supporters waving orange and blue signs, vowing to defeat an amendment that voters in 30 other states have passed without exception, including California and Maine.

"It is your right to love who you please; the government should not be matchmaker," said Rep. Keith Ellison, D-Minn.

Minnesota for Marriage has already launched a relentless campaign of phone banking to reconnect with supporters and remind them to vote Nov. 6.

"The bottom line, rallies don't win elections, getting people to the polls does," said Chuck Darrell, spokesman for the group.

His group's campaign workers already had made thousands of calls over the weekend and will continue an almost unbroken string of phone banking shifts until Election Day, Darrell said. The campaign also released a new radio ad Monday, urging people to vote and reminding them not to leave the question blank.

A unique quirk in Minnesota law means that a ballot question must win 50 percent of all ballots cast. That means if a voter skips the question, it is counted as a no vote. Over the years, that twist has snuffed out several ballot questions that got more than 50 percent of marked votes.

While same-sex marriage is already illegal in Minnesota, supporters say the amendment is necessary to block judges or legislators from changing that.

Opponents argue the measure will needlessly make it harder for loving and committed gay and lesbian couples to someday marry.

Minnesotans United for All Families, which hosted Monday's rally, is taking a multiple-pronged approach that will feel more like a traditional political campaign. Along with a multimillion-dollar ad campaign running until Election Day, the group will be kicking off a statewide tour in a recreational vehicle later in the week. The campaign has phone banks cranking up around the state, and local politicians plan to pop in to energize the troops.

In a pitch to woo Republicans to vote against the measure, conservative CNN analyst Margaret Hoover will be in town to host a fundraiser and campaign against the amendment. Hoover is a great-granddaughter of former President Herbert Hoover.

In many ways, the rally was a festive final chance to stoke supporters and get them fueled up for the final push.

Minnesota Vikings punter Chris Kluwe, wearing a stocking cap, sandals and a Vote No T-shirt, called it a "stupid, absolutely stupid" constitutional amendment.

Others made more personal pleas.

"My mom is a lesbian, and I want to make sure she has the same rights as I do," said VerLaine Henn, 42, of St. Paul.

Her mom smiled and said she was proud to have her daughter at her side.

"This is not really a gay issue, it is also a civil rights issue," said Claire Henn, 66. "We can't put discrimination into the constitution."

Baird Helgeson • 651-925-5044#