North Korea needs to get rid of its weapons to move forward, President Bush said Friday, and the international community needs to send a "loud and clear" message that it won't tolerate Pyongyang's actions.

"It's your choice, Kim Jong II. It's your choice to make," Bush said while taking questions from reporters at Chicago's Museum of Science and Industry during his first press conference outside the nation's capital.

The president urged the international community to put pressure on North Korea but stressed that diplomacy will take time.

"I believe it's best to make that choice clear to him with more than one voice," Bush said. "What I believe is we can solve the problem diplomatically."

He faced questions about how his administration will deal with the growing crisis with North Korea on a two-day swing through the Windy City in hopes of giving a boost to the state Republican Party.

"These problems didn’t arise overnight and they don’t get solved overnight," Bush said.

The United States needs international partners such as China and South Korea to back it up on pressuring North Korea, he said, adding, “I’m not going to let us get caught in the trap of sitting at the table alone with North Korea.”

Bush said military commanders told him that the United States had a “reasonable chance” of shooting down a missile fired by North Korea.

“Our anti-ballistic missile systems are modest, they’re new,” he added. "It’s hard for me to give you a probability of success."

The visit comes a day after Bush worked the phones with international leaders in an attempt to build a unified response to North Korea’s missile tests.

“My message was that we want to solve this problem diplomatically, and the best way to solve this problem diplomatically is for all of us to be working in concert," Bush said.

North Korea tested seven missiles on Tuesday, including a long-range Taepodong-2, which could reach U.S. soil.

Bush wants international pressure on the North Korea leader to “adhere to international norms. We expect you to keep your word.”

Bush said he supports Japan’s draft U.N. Security Council resolution to impose sanctions on North Korea.

The president also addressed the threat posed by Iran on Friday.

"The problem in North Korea and the problem in Iran is their leaders have made choices and by what we’re saying is, 'there is a better avenue for you,'” Bush said.

The news conference is the latest step in an attempt to promote the president’s agenda and boost his job approval numbers. Bush took questions from national reporters and Chicago media.

"We're going to mix it up," said White House press secretary Tony Snow.

Most reporters asked about North Korea, with a few queries about Chicago politicians.

Bush opened with a 15-minute statement touting a strong Chicago economy and urging Congress to offer comprehensive immigration reform.

“We are a land of immigrants,” Bush said, asking lawmakers to negotiate legislation that would offer a temporary guest worker program.

House and Senate negotiators are trying to reconcile immigration reform legislation to address millions of illegal immigrants currently residing in the United States. The Senate passed its version on May 25 that would offer a temporary guest worker program while the House version, passed last December, includes improvements on border security.

Bush said immigration was one of the top issues in this midterm election year. "The system we have now isn't working," he said.

The president also addressed the War on Terror and the war in Iraq.

“We will lose if we leave too early,” Bush said. “A free Iraq is going to help inspire others.”

Later on Friday, Bush will head to a Republican fundraiser for gubernatorial candidate Judy Baar Topinka, the state treasurer trying to unseat Democratic Gov. Rod Blagojevich. The president then is scheduled to speak on his American Competitiveness Initiative before heading back to the White House Friday night.

A reporter questioned whether Bush's appearance at the fundraiser could hurt Republicans in the November elections.

"We will hold the House and the Senate," Bush said. "You win elections by believing something. You win elections by having a plan to protect the American people from terrorist attack. ... I'm looking forward to these elections."

Bush arrived in Chicago Thursday night and spent his 60th birthday away from home.

Chicago Mayor Richard M. Daley and business leaders gave the president a birthday cake after dinner at the Chicago Firehouse.

The trip comes ahead of similar visits for the rest of the summer for Bush, said White House counselor Dan Bartlett.

"Oftentimes when you fly into a community, you're in and out within 55 minutes and you talk about one subject," Bartlett said. "This gives him an opportunity to cover a broader range of subjects in the local community."

FOX News' Wendell Goler and The Associated Press contributed to this report.