President Obama and his surrogates are working hard to repair their relationship with organized labor, as Democrats kick off their first official day of the national convention Tuesday.

Organized labor, which helped carry Obama into the presidency in 2008, has felt jilted in recent years -- over the president's decision to stall the Keystone XL pipeline, the Democrats' decision to hold the 2012 convention in union-unfriendly North Carolina and other moves.

Some top union leaders are still in the Obama corner, but the president and his team are making sure to show the love as the labor movement signals it may lay low this year. The opening day line-up of speakers at the Democratic National Convention in Charlotte will feature Michelle Obama and keynoter San Antonio Mayor Julian Castro -- the unions, though, are not playing a central role this week.

So in a Labor Day appeal to that valuable contingent, President Obama on Monday traveled to Toledo, Ohio -- home of the GM transmissions factory and Chrysler-owned Jeep assembly plant -- in an attempt to woo union members, if not leaders.

"It is unions like yours that helped to forge the basic bargain of this country -- the bargain that built the greatest middle class," the president told the crowd. "I'm counting on you. I'm counting on you."

He also told attendees that the cornerstones of middle-class security -- including Medicare, Social Security and the 40-hour work week -- were made possible because "working people organized and mobilized."

Obama got some high-power backup in Toledo from AFL-CIO President Richard Trumka, who accused Obama's GOP rival Mitt Romney of pitting people against each other.

Vice President Biden told union workers Monday at a rally in Detroit that he and Obama have their backs, and then asked them to be critical toward Romney and running mate Rep. Paul Ryan.

"Romney and Ryan don't think that much about you guys," Biden said. "We know who built this country and we know who is going to rebuild it. It's you. Instead of vilifying you, we should be thanking you. We owe you."

The Romney campaign, though, put out a Labor Day message Monday questioning the president's commitment to America's workforce.

"Over 23 million people are struggling for work this Labor Day, and President Obama once again offered no new ideas for getting our economy back on track," campaign spokeswoman Amanda Henneberg said in a statement. "President Obama has a record of zero and 23 million, and it's time to get a new coach. Americans aren't better off than they were four years ago and are longing for a winning season. Mitt Romney has a serious plan to fix the economy and get people back to work."

The Obama administration's decision earlier this year not to approve permits for the Keystone XL pipeline roiled union leaders because building the Canada-to-Texas project would have created hundreds if not thousands of new, high-paying jobs.

They appeared so miffed by the Keystone and Charlotte decisions that they held a major non-convention event this summer in Philadelphia.

IBEW President Ed Hill said at the time that holding a Democratic convention in a right-to-work state such as North Carolina was a "wake-up" call about the party's regard for unions. However, union leaders have since rejected the notion that they held a "shadow convention" in protest.

Labor unions historically have been among Democrats' biggest supporters. And the party can little afford to lose such backing in the tightening race with Romney and his campaign, which has a decided cash-on-hand advantage with roughly 10 weeks remaining before Election Day.

Though the extent of the Obama-union rift is arguable, the North Carolina chapter of the AFL-CIO thought union workers were feeling so slighted this Labor Day -- considering the state is among the least unionized states in the country -- that it offered free hugs at a convention-related event in Charlotte Monday.

The so-called "Hug-A-Thug" was in part an effort to show members are valued employees that do important work, not "union thugs," as some Republicans have portrayed them.

"We're saying have a free union hug, bust the myth about thugs and together we can make America work," said Jeremy Sprinkle, the chapter's communications director.

Still, the national chapter is taking a decidedly scaled-back approach to this year's convention.

"We won't be buying skyboxes, hosting events other than the Labor Delegates meeting or bringing a big staff contingent," Trumka reportedly told union leaders last month in a letter.

The Service Employees International Union -- the country's largest health care union with more than 1.1 million members -- gave money to the 2008 convention and reportedly has given to this year's event.

However, SEIU President Mary Kay Henry released a statement Monday that appeared less than a whole-hearted endorsement for Obama.

"It is meaningless for elected leaders to deliver empty rhetoric about working people's contribution on Labor Day or any day without using their power in Washington to create an economy that works for all," she said. "Working people know what is at stake for this country. They want their elected leaders to move away from the soaring rhetoric and work for them. They want their contributions to be valued beyond Labor Day."