New polls released this week reveal President Obama holds a very tight lead over Mitt Romney, but that the GOP nominee is closing the gap by focusing on economic issues.

According to a Pew Research poll released Thursday, 50 percent of registered voters support or lean toward supporting Obama, while 46 percent support or lean toward Romney. That's a very narrow lead for Obama, given a margin of error that is plus or minus 3 percentage points.

Obama's lead is not statistically significant in a new Associated Press-GfK poll, also released Thursday. Obama earns 47 percent in that poll, compared to 44 percent for Romney, a result that falls within the poll's margin of error.

Three polls released this week, including the Pew and AP-GfK surveys and a Bloomberg National Poll released earlier, indicate Obama is vulnerable on the economy. In the Pew poll, the only question where Romney beat Obama was on who would do a better job "improving economic conditions."

Romney has made the economy the centerpiece of his campaign. It's the focus of his stump speech and campaign events. Even when making his case to specific voting blocs — such as Hispanics or women — Romney frames his argument in economic terms.

The Pew survey also found that Republican voters are paying more attention to the election, but that Democrats are more satisfied with their candidate. That holds true in the recent Bloomberg poll as well.

In that poll, Obama appeared to hold a 13-point lead over Romney, 53-40, but also blew him out of the water when it came to enthusiasm, with 51 percent of Obama supporters describing their support as "very strong" compared to 35 percent of Romney's supporters who would describe their own support that way.

Still, the Pew poll found that Republican voter enthusiasm is high when it comes to disliking their other option, since 91 percent of Romney supporters have an unfavorable opinion of President Obama and a strong 53 percent have a "very" unfavorable opinion.

But despite signs that this will be a very close race, most voters think Obama will win. According to Pew, half of registered voters (52 percent) still think Obama will win, while 34 percent think Romney will take the White House in November. In the AP-GfK poll, 56 percent thought Obama will win.