Sen. Barack Obama, D-Ill., warned Democratic activists Sunday that the party must take a tougher stance on national security if it wants to succeed in the November elections.

"What Democrats have to do is to close the deal," said Obama, the keynote speaker at Iowa Sen. Tom Harkin's 29th annual steak fry. "We have got to show we have a serious agenda for change."

Obama's appearance in Iowa, where precinct caucuses launch the presidential season, has raised a number of eyebrows about his intentions for a presidential run in 2008. Though only a first-term senator, Obama has burst onto the national scene.

But he wouldn't say Sunday whether he was considering a run at the White House.

"My only attentions right now are focused on '06," said Obama. "Whoever is looking toward 2008 without focusing on 2006 makes a mistake."

Former Virginia Gov. Mark Warner also spent Sunday afternoon at the steak fry, and left little doubt that he is looking ahead to 2008.

"You know and I know that it all starts in Iowa," Warner told the audience. "Do your part. We're going to take back the Congress this year and then we're going to take back our nation."

Warner accused President Bush of using the anniversary of the Sept. 11, 2001, terrorist attacks to inject the issue of terrorism into the 2006 race. Warner said the strategy is proof that the GOP is nervous and trying to scare voters.

"I think Americans feel President Bush missed an opportunity on the fifth anniversary of 9/11 to bring our country together, to call us to some level of common cause and shared sacrifice," Warner told The Associated Press.

Obama said he and other Democrats want to take the nation in a different direction, but he vowed not to "demonize" Republicans. He said a carefully cast message could lure moderate Republicans who are uncomfortable with the White House's hard-line conservative stance.

"The American people are ready for change," he said. "The American people recognize the path (of) the last five years has not made us more competitive, has not opened more opportunities and has not made us safer."

Obama called the attention he has received "flattering," recalling how he was treated like a hero when he traveled to Kenya this summer to visit his father's home village. He also noted that rumors of his presidential ambitions began the day after he was elected to the Senate in 2004, when someone asked him about his plans for 2008.

"I said you'll have to wait a little while," he said.

In his speech to more than 2,000 activists gathered in a county park, Obama also warned that many voters are losing hope that the government is on their side.

"Even those of us in public life get a certain cynicism," he said. "We've got a lot of self-important leaders who are long on rhetoric and short on ideas.

"People still believe that in America the promise is limitless, but they aren't sure their leaders do."