Can Obama persuade voters to turn to him again?

Editor's note: Ruben Navarrette Jr. is a CNN contributor and a nationally syndicated columnist with the Washington Post Writers Group. Follow him on Twitter: @rubennavarrette

Charlotte, North Carolina (CNN) -- As thousands of Democrats gather in Charlotte this week for their party's convention, hope and change need to make room for humility and contrition.

There is a lot to be humble and contrite about. Like George H.W. Bush in 1992, President Obama seems to be out of ideas. By any measure, this is a failed presidency. And Obama has compounded that failure by continuing to blame his predecessor for the situation he inherited, in a ploy that is well beyond the expiration date.

The economy continues to be weak. Gas prices are high. Consumer confidence is low. Many people are afraid of losing their job, their home and their life savings. We worry about the present, and we worry even more about our children's future.

Ruben Navarrette Jr.

Campaign promises were broken. A president who vowed to bring Americans together has driven us further apart with divisive rhetoric that fuels class warfare.

Meanwhile, Obama's foreign policy successes -- i.e., the killing of Osama bin Laden by Navy Seals -- have been offset by the president's indecisiveness in dealing with Iran and Syria. And this administration has not been as good a friend to Israel, or as respectful to Prime Minister Benjamin Netanyahu, as it should have been.

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One of the biggest mistakes that Obama made in the last three and a half years was not taking better care of his base and adhering to the principles he espoused when running for the presidency. He has disappointed many parts of the coalition that helped elect him. After eight years of George W. Bush, liberals and progressives thought they would get their concerns alleviated by Obama. Instead, when Obama began to embrace some of Bush's policies, some of his supporters ended up with new concerns. Many on the left have registered their disappointments.

Civil libertarians winced when Obama emulated George W. Bush's blueprint for fighting the war on terror, everything from suspending habeas corpus for terror suspects to domestic wiretaps to keeping open the military prison at Guantanamo Bay.

Latinos are heartsick over the fact that Obama deported more than 1.5 million illegal immigrants (most of them from Latin America) and broke up hundreds of thousands of families. Teachers unions were upset when Obama adopted the high-stakes testing accountability model that formed the basis of "No Child Left Behind" and rebranded it as "Race to the Top." And gays and lesbians would have likely preferred someone who helped lead the repeal of the Defense of Marriage Act over someone who merely announced that he had come around to personally supporting gay marriage.

Polls show that many Americans still like President Obama as a person. In August, a USA Today/Gallup poll showed that voters found Obama more likable than Mitt Romney by a staggering 23 points, 54 percent to 31 percent. But few seem to trust his abilities. The same poll found that Romney got the better of Obama when voters were asked who they thought was better able to fix the economy, 52 percent to 43 percent.

Will disillusioned Democrats and independents who feel hoodwinked show up to vote for Obama in November? That's the question.

As usual, former Republican presidential candidate Newt Gingrich is sure that he has the answer. Gingrich told conservative radio talk show host Sean Hannity: "Obama won't be defeated by those who are angry with him. He'll be defeated by those who are disappointed in him."

That sounds right. And that is what this week is all about, inspiring the base to vote and cobbling together the same winning coalition that helped elect Obama in 2008.

At this convention, there will be no need for Greek columns or Messianic rhetoric. Democrats can't re-capture lightning in a bottle. But Obama might be able to persuade just enough voters to take a chance again, and that would be good enough. To do it, he has to reconnect with everyday Americans by:

-- Showing that he "gets" it, and that he is ready to do something different in his second term than what he did in his first one,

-- Accepting responsibility for his failures, admitting his mistakes and showing that he has learned from both,

-- Uniting, inspiring and motivating the Democratic base to turn out and vote despite his center-right drift on a host of issues,

-- Showing empathy for those who are suffering and giving them hope that things will improve.

Last week, in Tampa, Romney needed to zero in on those who thought Obama had failed as president, but who were not yet sold on the idea of him as a replacement. He did some of that.

This week, in Charlotte, Obama needs to speak to those who don't like the alternative but still think he has come up short and needs to do better. We'll see if he can do that.

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The opinions expressed in this commentary are solely those of Ruben Navarrette Jr.