A new internal poll from Democratic Sen. Claire McCaskill’s campaign showed her with an expanding lead over GOP Rep. Todd Akin.

The poll had McCaskill leading by 14 points, 52 percent to Akin’s 38 percent, a substantial increase over the last internal numbers released from the same pollster, which showed her with a 9-point lead.

The tracking survey, which pollster Kiley & Co. said was finished this evening, suggested McCaskill’s campaign is succeeding in driving up the unfavorable perception of Akin. Her campaign has launched an aggressive effort to attack the Republican on an assortment of policy issues, highlighted by last week’s ads that featured victims of sexual assault criticizing Akin’s position against emergency birth control.

“Voters are much more likely to say that their opinions of Congressman Akin have grown less favorable (50%) rather than more favorable (21%), based on what they have heard or read in the last two weeks. Another 23% say their opinions have not changed,” the pollster wrote in a memo.

The memo also indicated the poll found Akin has failed to gain ground with independent voters. It featured interviews with 601 likely voters and had a margin of error of 3.5 points. McCaskill’s internal polls and outside surveys differ significantly from internal figures circulated by the Akin campaign, which have shown him with a small lead.

Akin has not released any fundraising numbers for the third-quarter filing period that closed Monday, leading to the suspicion that his totals will be weak. McCaskill has reported raising $5.8 million in the quarter.

Roll Call rates the race as Leans Democratic.