Republican presidential candidate John McCain chided his Democratic rival on Wednesday for getting "a little testy" as Barack Obama sharpened his tone amid a tightening White House race.

"I honor his service. I don't honor his policies. I don't honor his politics," Obama said, taking on his GOP opponent with renewed vigor while some Democrats fret that their candidate has not been aggressive enough.

As the campaign turns increasingly negative, both candidates unveiled fresh attack advertisements ahead of their back-to-back national conventions.

Again trying to tie McCain to the unpopular President Bush, Obama's TV commercial asks: "Can we really afford more of the same?" It slams McCain's tax plan as a giveaway for big corporations and oil companies. McCain's radio ad claims: "Celebrities like to spend their millions. Barack Obama is no different. Only it's your money he wants to spend."

Democrats privately and publicly are questioning whether Obama has a second act beyond his message of change and wondering whether he can throw an effective punch against a Republican Party willing to play hardball.

Republicans, in turn, are emboldened by improving poll numbers: Even ardent critics of McCain's campaign see a way he could win although Bush's unpopularity remains a drag and war and economic distress have created a dreadful political environment for the GOP.

New national polls show McCain starting to close a summer-long Obama edge.

The Pew Research Center's latest survey found Obama at 46 percent and McCain at 43 percent, tighter than the 8 percentage point gap just two months ago. The survey found that McCain has solidified his base support, particularly among whites, men, Republicans and evangelicals. Conversely, Obama has made few gains, but has retained his overwhelming advantage among blacks and younger voters, while also leading among women.

After struggling to find his footing, McCain has put Obama on defense over the past few weeks.

In ads and speech, he worked to plant the idea in voters' minds that Obama lacked the experience and substance to be president. McCain also reversed himself to support offshore drilling amid high gas prices, and that new message has helped unite dispirited Republicans.

More recently, the Arizona senator struck a hawkish stance during Georgia-Russia conflict in the hope of turning the campaign conversation to his strength _ national security. And, he delivered what was widely viewed as a strong performance last weekend before an audience of evangelicals, a Republican core constituency he has struggled to energize.

Even so, he still has found himself on the defensive at times in trying to shed his association with Bush _ a link Obama and the Democrats are making at every turn. A recent AP-Yahoo poll showed that six of 10 adults say that McCain will follow Bush's policies. Thus, McCain recently launched a TV ad stressing that he knows the country's worse off than it was four years ago and asserting: "He's the original maverick."

Obama has been criticizing McCain for months, though he's used humorous lines and a light touch to blunt the attacks on the campaign trail. He's also run critical TV ads, though more spots were positive than negative compared with McCain.

Then last week, Obama started airing more hard-hitting TV and radio ads against McCain that were tailored to individual media markets. Some featured pictures of McCain and Bush, while others accuse McCain of ignoring the hardships of the working class, failing to protect jobs, and catering to oil companies.

Obama aired 10,000 spots last week, of which almost 9,000 were anti-McCain, according to Evan Tracey, who tracks political ads as head of TNS Media Intelligence/Campaign Media Analysis Group. During the same period, McCain aired virtually all anti-Obama ads; of his 13,000 spots, only 302 didn't mention Obama.

This week, the Illinois senator returned revived from a Hawaiian vacation and stepped up his criticism of McCain _ sending a message to supporters that he's up to waging a fierce fight.

On Monday, a feisty Obama called the economy a disaster thanks to "John McCain's president, George W. Bush" and methodically tore into McCain's health care, tax and offshore oil drilling policies. He said McCain arrived at his new offshore drilling position "when he started looking at polling."

A day later, Obama said McCain "doesn't know what he's up against," asserted that his rival was questioning his "character and patriotism" in his Iraq war stance and challenged McCain to stop.

"I have never suggested that Sen. McCain picks his positions on national security based on politics or personal ambition. I have not suggested it because I believe that he genuinely wants to serve America's national interest. Now, it's time for him to acknowledge that I want to do the same."

McCain countered Wednesday, saying: "Sen. Obama got a little testy on this issue. He said I was questioning his patriotism. Let me be clear _ I am not questioning his patriotism. I am questioning his judgment."

McCain then pressed his attack. "Washington is full of talented talkers," McCain said. "The bottom line is that Sen. Obama's words, for all their eloquence and passion, don't mean all that much."

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Associated Press Writers Jim Kuhnhenn in Washington, Beth Fouhy in Martinsville, Va., and Philip Elliott in Las Cruces, N.M., contributed to this report.