CHARLOTTE, N.C. -- The airplane carrying Democratic presidential candidate Barack Obama made a precautionary landing in St. Louis on Monday after the crew had a problem keeping the nose up on takeoff from Chicago.

The plane, an MD-80 Midwest charter, struggled to keep the nose at the necessary angle, as it left for Charlotte, N.C., the pilot said. Later, Midwest Airlines said the problem developed because an emergency slide located in the tail cone of the plane deployed in flight and never threatened the safety of the flight. The National Transportation Safety Board said it planned to investigate the incident.

Federal Aviation Administration spokeswoman Laura Brown said the plane did not declare an emergency but "requested a diversion for mechanical issues they called a flight control problem."

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VIDEO: Obama Cancels Visit To Charlotte After Plane Makes Unscheduled Stop

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After landing, Obama read the paper in the front cabin, but ventured briefly to chat with the press at one point.

"I just thought we'd spice things up a little bit today," Obama joked.

The Illinois senator and a small entourage eventually left the plane to wait out the maintenance at a local hotel; the North Carolina trip was postponed. But he called the Charlotte event to apologize for his absence and summarize his speech on the nation's economic woes (see below). He expanded on that economic message later to his traveling press corps here in Missouri, a battleground state he hopes to win in the fall.

"I'm so sorry that I'm not down there," Obama said in the telephone call. "We had a little glitch in our plane." He promised to visit Charlotte soon.

Obama had two fundraisers in Atlanta scheduled for Monday evening.

Upon takeoff from Chicago, passengers had felt the plane dip briefly, causing a stomach-rolling sensation like being on a roller coaster, but the unexpected movement didn't alarm the frequent fliers on board.

Later, the pilot said, "We detected a little bit of controllability issue in terms of our ability to control the aircraft in the pitch, which is the nose up and nose down mode." His name was not released in accordance with Midwest policy.

"The autopilot and the aircraft are just fine. As we descended, whatever was inhibiting our ability has now been rectified. However, just for safety purposes we are going to be stopping in St. Louis and making sure that there's nothing binding our controls," he said.

The landing at 9:51 a.m. CDT was normal.

Obama, his staff, the Secret Service entourage and the press sat on the plane for over an hour as it was being checked out at Lambert Airport.

During his visit with reporters, Obama shook his head "no" when asked if he was worried.

"Anytime a pilot says something's not working the way it's supposed to, then you make sure you tighten your seat belt," Obama said. "Everything seemed under control. The pilots knew what they were doing."

Obama's campaign charter hasn't made a precautionary landing before.

"This is a first," he said.

Obama Lumps McCain In With Bush On Economy

Obama was scheduled to visit with families at James Martin Middle School in Charlotte just after noon. Campaign officials at first thought there would only be a 45-minute delay, but the invitation-only event was officially postponed around 12:30 p.m. No new date has been announced although the presidential candidate promised to visit soon.

“I’m disappointed, but at the same time I know he'll be back and I’ll see him then,” said Obama supporter Cameron Patriarca.

A short time after the event was canceled, Obama addressed the crowd over the phone.

“Although we're going through tough times now, it is not inevitable that we continue these tough times,” he said.

For eight minutes he talked about fixing the economy for the working class.

“What I want to say to you is that help is on the way,” he said.

Obama had planned remarks that blame Washington for the country's economic woes and sought to link Republican rival John McCain to President George W. Bush's policies as the presidential candidates maneuvered for the upper hand on a top concern of voters. He elaborated on some of those ideas in Missouri on Monday afternoon.

"It hasn't worked, it won't work, and it's time to try something new," Obama said of the country's current economic policies under a GOP president.

The economy, and especially its impact on the middle class, has emerged as the central focus of the presidential campaign, given skyrocketing gas prices, high job losses and rising food costs. Both candidates were launching weeklong efforts to highlight their differences on the issues.

Both Obama and McCain sought to send a message to those feeling the biggest economic pinch: I feel your pain.

Obama lamented job losses and foreclosures. The text of his speech said: "For millions of families, these everyday worries and long-term anxieties have grown considerably worse over the last year."

He also took a swing at McCain and Bush in the remarks, lumping the two Republicans together.

"As our world and our economy have changed, only Washington has stood still. The progress we made during the 1990s was quickly reversed by an administration with a single philosophy that is as old as it is misguided -- reward not work, not success, but pure wealth," Obama said, arguing that Bush policies were skewed toward big corporations and multimillionaires.

He said that strategy has failed badly and that McCain offers "exactly what George Bush has done for the last eight years."

Obama chided McCain for saying at one point that the country has made "great progress economically" under Bush. "He believes we're on the right track," Obama said of McCain.

"I won't stand here and pretend that we can or should undo the economic transformations that have taken place over the last few decades," Obama said. "There are jobs that aren't coming back and this world will always be more competitive. But I do believe that if all of us are willing to share the burdens and benefits of this new economy, then all of us will prosper -- not just because government makes it so, but because we're willing to take responsibility as individuals to work harder and think more and innovate further."

He called anew for the passage of "a second stimulus package that provides energy rebate checks for working families, a fund to help families avoid foreclosure, and increased assistance for states that have been hard-hit by the economic downturn." He also renewed his call for McCain to support such a package.

"There are many policies we'll disagree on, but immediate relief for families who are struggling shouldn't be one of them," Obama said.

On taxes, he said: "It's time to reform our tax code so that it rewards work and not just wealth." Again referring to McCain, he added: "The difference is -- he trusts that prosperity will trickle down from corporations and the wealthiest few to everyone else. I believe that it's the hard work of middle-class Americans that fuels this nation's prosperity."

Doug Holtz-Eakin, a McCain senior policy adviser, responded to Obama's criticism, saying: "While Barack Obama campaigns on a promise of no tax hikes for anyone but the rich, we once again find that his words are empty when it comes time to act."

McCain also spoke about the economy Monday in Denver. He’s proposing tax credits for families who buy health insurance.