A new poll suggests Barack Obama is gaining ground on Hillary Rodham Clinton ahead of Pennsylvania's April 22 Democratic primary.

Candidates Compared | Polls Tracked

Two weeks out, Clinton remains in front with 50 percent, but her margin continues to shrink in this survey -- from 9 percentage points a week ago and 12 percentage points in mid-March. Obama remains more popular among the state's black voters, 75 percent to 17 percent, and Clinton does better among whites, 56 percent to 38 percent. As in past surveys, Clinton leads among older voters and Obama leads among younger ones.

A new American Research Group poll has the two tied in Pennsylvania at 45 percent, with undecideds and those preferring other, unnamed candidates making up the balance. A similar March 8 survey had Clinton leading Obama 52-41 percent. Obama leads Clinton 53-36 percent among men, while among women, Clinton leads 52-39 percent, ARG said. Clinton leads 52-36 percent among white voters while Obama leads 89-9 percent among blacks.

Last week, Rasmussen Reports also showed the race tightening.

Rasmussen said support for Clinton slipped from 52 percent early in March, to 51 percent in mid-month, 49 percent a week ago, and 47 percent on April 1. Support for Obama has increased from 37 percent to 42 percent in the same time period. Obama recently received a key endorsement from Pennsylvania Sen. Bob Casey and has also spent more on television ads than Clinton, Rasmussen said.

The latest SurveyUSA poll shows Clinton's lead shrinking from 19 percentage points to 12 percentage points compared to a similar poll three weeks ago. The movement comes almost entirely from men, Survey USA said. Among that demographic, Clinton had led by 5 percentage points but now trails by 7 percentage points.