New York Mayor Michael Bloomberg is demanding the Obama administration increase enforcement of the nation's gun laws, escalating his longtime push on the issue in the wake of the last month's shooting rampage in Arizona.

The mayor's office hired private investigators to buy guns at a gun show in Phoenix, and Bloomberg then played video of the sting at a press conference on Monday in New York. It depicts a man who is sold a gun even after he acknowledges that he would not be able to pass a background check, which would violate federal law.

It's not clear the ease of buying guns at these shows would have prevented the shootings in Tucson, as alleged killer Jared Loughner legally purchased a Glock 19 semiautomatic handgun from a gun store in November.

But Bloomberg has long advocated increased funding and attention to enforcing gun laws, arguing many crimes in New York City and other major cities involve the use of guns by people who should not be allowed to purchase them because of criminal records.

And he is now on a media blitz to push Obama on the issue. The White House has said Obama will soon "address" the issue of gun control, but it has been vague on exactly what he will say or whether he will propose any additional funding or new laws.

"The president should stand up" on gun issues, Bloomberg said in an appearance Tuesday on "The Rachel Maddow Show." He added, "It's one of the issues he can build a legacy on."

Obama today



The president will sign the START nuclear weapons treaty with Russia that he strongly pushed in November and December. He will also hold a private meeting in the Oval Office with one of his strongest opponents, Sen. John McCain (R-Ariz.). Aides said the pair will speak about a broad range of issues.

Happy talk



Outside of Obama's very serious words about Egypt, the White House has adopted an optimistic tone, while leaving Republicans to sound the alarm about problems such as the growing deficit. Here's a look at the difference in rhetoric by John Dickerson of Slate:

"Now, instead of tough talk, the president is offering stirring slogans. 'Win the future' was the theme of his State of the Union address. 'We do Big Things' is now on T-shirts available to Obama donors. 'Startup America' was unveiled Monday to encourage entrepreneurs. If the first lady hadn't taken "Let's Move" for her anti-obesity campaign, it could have been used for the president's push for high-speed rail.

"The president has decided that he'll let Republicans be the dour ones. A credible deficit-reduction plan is no longer a precondition for weeks of talk about plans for government investment. Let Rep. Paul Ryan, chairman of the House Budget Committee, do all that gloomy talking about the grim fiscal picture. As one GOP aide put it after the president's State of the Union speech and Ryan's official response: 'He's the optimistic one, and we're the ones that want to lock up your children.' "