CHARLOTTE, N.C -- America’s two major political parties are prisoners of their images, stifling their ability to broaden their appeal.

Democrats are routinely portrayed as liberals and Republicans as conservatives, and movement toward the center, where elections are usually won, is difficult to detect.

The image problem dogs both parties. Each met last week for the first time since the November elections, and each pledged to work hard to welcome others. But each confronts a challenge.

Being firmly left or right does play well in a lot of places, particularly on the day’s most prominent issues, such as immigration, gun control and debt reduction. Being left or right is also important to party activists, the folks who raise and contribute money and provide crucial volunteer manpower. But as appealing as lines in the sand are to the faithful, they make it hard to sell the parties to everyone else.

That’s why, despite senators from both parties trumpeting a plan Monday to revamp immigration laws, prospects for passage in the Republican-led House of Representatives remain shaky. It’s why the chances of Congress enacting new measures to dramatically curb the sale and use of guns are uncertain at best.

The ideological polarization makes expanding the parties difficult, and the more that leaders seem to appeal to those bases, the harder it gets to broaden the parties’ appeal.

The Democratic Party “is suffering from perceptions about Obama,” Kansas Democratic Chairman Joan Wagnon said. “It’s about fear-mongering, and it’s about this notion that people are losing control over their lives to Washington.”

In such states, voters tend to see President Barack Obama as the champion of big, obtrusive government, a talking point that conservatives will be highlighting as major elements of the 2010 health care law, which requires nearly everyone to get coverage next year or pay a fine, kick in.

Republicans have the bigger challenge. A CNN/ORC International poll last month found that 53 percent thought the party was too extreme, compared with 37 percent – still a sizable amount – who saw Democrats that way. The conservative hard line on immigration and guns doesn’t help in more moderate states.

“I don’t think we’re intolerant, but that perception needs to be addressed,” New Hampshire Republican Chairman Wayne MacDonald said.

Solutions include changing not only the rhetoric, but also the tone. Why, former House Speaker Newt Gingrich asked, do conservatives always sound so angry?

“We can win the argument if we go back to the Republican tradition of being happy warriors,” he said.

Among Democrats, the message needs to be less about philosophy and more that “We care about people. We care about seniors, about health care,” said Texas state Rep. Senfronia Thompson.

This left-right split won’t evaporate overnight, and probably not for years. Its roots are deep.

Until the 1980s, coalitions would come and go in Washington, depending on the issue. Major civil rights legislation passed not with Democratic unanimity but with the support of moderate Republicans. Foreign policy matters were bipartisan, and many Republicans were open to tax increases.

Today, though, Washington politicians are on one side or the other, reflecting their strong constituencies.