BRIAN WILLIAMS: In this country, April 15, it's Tax Day, or tax extension day for some. For others, this was Tea Party day. All across this country, Americans gathered in parks and plazas and in Washington, D.C., to show their government they're fed up with the way things are going. Our own Kelly O'Donnell is with us from the National Mall tonight. Kelly, good evening.

KELLY O'DONNELL: Good evening, Brian. For the Tea Party movement, this is something of a political holiday, using Tax Day to make their case. They don't like where the country is headed. They don't like the size of government, and more than one was willing to tell me they don't like the media. But they all do want to be heard. Going right to the source, Tea Partiers rallied in Washington, the very place their movement wants to change.

TOM TERRY, TEA PARTY ACTIVIST: Five years ago, I would never have been here. Now, I feel a responsibility to stand up and at least with these other folks here, and say someone listen.

O'DONNELL: Wading through the crowd, there are at least two different kinds of issues – all the political distrust. Is it frustration, anger?

LINDSAY FLOWER, TEA PARTY ACTIVIST: Total frustration, total frustration with a health care plan that does nothing to reduce costs.

O'DONNELL: And skepticism over how the Tea Party is judged and labeled.

SHIRLEY FORD, TEA PARTY ACTIVIST: We're not racists, we're not any of the above that people claim us to be. We're ordinary citizens that love our country, and we're fighting for it.

UNIDENTIFIED MAN: I've lost count how many Tea Parties I've been to.

O'DONNELL: With rallies across the country today, the Tea Party mobilized a year ago in opposition to health care reform, government spending and taxes.

O'DONNELL, TO MAN: There aren't a lot of African-American men at these events.

DARRYL POSTELL, LAUGHING: Right.

O'DONNELL: Have you ever felt uncomfortable?

POSTELL: No, no, these are my people, Americans.

O'DONNELL: A new CBS News/New York Times poll finds 18 percent of Americans say they support the movement. Within that group most are white men over 45, better educated and wealthier than the general public.

O'DONNELL: Do you think this has enough energy to really last to November and to make a difference?

RICK WILLMORE, TEA PARTY ACTIVIST: Yes. Oh, yes.

O'DONNELL: Why?

WILLMORE: Because it's the people. It's not a party. It's the people. The people are angry and they're organized.

O'DONNELL: Rallies like these were held all over the country today, from Denver to Chicago, Wisconsin to Alabama. And in the poll and conversations I had today, Tea Partiers say they don't want to see this movement become a formal third party, but do hope they can influence elections.

GEORGE STEPHANOPOULOS: We're going to turn to politics now, and the political storm this tax filing day. Members of the Tea Party movement have zeroed in on April 15, calling attention to what they say are sky high taxes and a bloated government. Tea Party rallies were held in several cities today, the biggest one in Washington, and Jon Karl was right in the middle of it.

JONATHAN KARL: Meet the Tea Partiers: a nurse from Pennsylvania with her daughter, an American Airlines pilot from Texas with his son, a property manager from Atlanta. I mean, why are you here? What's the one issue that-

UNIDENTIFIED WOMAN #1: Why am I here? Because I work hard. It's my money. I want my money to go where I want it to go.

KARL: They came to Washington, angry about President Obama's policies, to be sure, but also angry at the way they've been portrayed.

UNIDENTIFIED MAN #1: We've been called racist. We've been called everything.

UNIDENTIFIED WOMAN #2: Don't even, we've been called a lot of things we're not.

UNIDENTIFIED MAN #1: The only thing we want is Obama to be more cautious with our money and not be wasteful. That's it. It doesn't make us racist.

KARL: Many of them blamed us, the news media.

UNIDENTIFIED WOMAN #3: You know what, back off, back off.

UNIDENTIFIED MALE VOICE: Where is the angry mob?

UNIDENTIFIED WOMAN #3: Give us some space. We don't want to talk to you.

UNIDENTIFIED WOMAN #4: We want honesty from you. We want fair time from you. We want you, the media, to represent all the people, not just a certain portion of the people.

KARL: No shortage of passion here – from the Tea Party critics, too.

UNIDENTIFIED MAN #2: But don't come out here and say that you're speaking for all Americans when you don't.

KARL: Is that what you guys are saying, that you represent all Americans?

UNIDENTIFIED MAN #3: We represent a majority of Americans. It's not Obama. It's not, it's against Bush, as well. These people were mad at Bush, which is why-

UNIDENTIFIED MAN #2: The sign here says "Impeach Obama." The sign here says "Repeal ObamaCare." You can't tell me that this is not against President Obama.

KARL: There was disagreement among the Tea Partiers themselves. This woman thought a fellow Tea Partier's poster went way too far.

UNIDENTIFIED MAN #4: I wasn't degrading him at all. I was just saying that-

KARL: Well, now, wait a minute. By comparing somebody to Adolf Hitler, you're degrading him.

UNIDENTIFIED WOMAN #5: Well, that's my point. And that's what I said. If you look around, though, there are literally thousands of signs that say nothing about Hitler, say all about how we're going to get even in November.

KARL: Here at another Tea Party rally in Washington, D.C., a group of activists is going to unveil the Contract from America, outlining the movement's top 10 demands. One of those demands, George, is to do away with the entire federal tax code and replace it with one no longer than 4,543 words long. That's the length of the U.S. Constitution.

STEPHANOPOULOS: Okay, echoes of 1994 and the Contract for America. Jon Karl, thanks very much.