Two of the surveys show Sen. Pat Toomey (R., Pa.) with a one-point lead over Democrat Katie McGinty, while a third shows a three-point advantage for the challenger. The surveys mirror what political veterans say privately: that a  race that could help determine control of the Senate is likely to go down to the wire.

All three polls showed the race within their margins of error.

A Mercyhurst College of Applied Politics poll out Monday found Toomey leading 43 percent to 42 among registered voters. (It surveyed 420 registered voters between Sept. 12 and 23 and has a margin of error of 4.8 percent).

Similarly, a Muhlenberg College/Morning Call poll released over the weekend showed Toomey gaining ground and moving into a lead, 41-40. The same poll found McGinty with a five-point edge just a week earlier. (This poll surveyed 486 likely voters between Sept. 9 and 23 and has a 5 percent margin of error).

Meanwhile, a CNN/ORC poll released Monday morning found McGinty with a three-point edge. It found she had 49 percent support among likely voters compared to 46 percent for Toomey. (That finding was based on questions to 771 likely voters, and has a margin of error of 3.5 percent).

Toomey' surge in the Muhlenberg poll coincided with Hillary Clinton slipping and Donald Trump gaining in Pennsylvania. One week ago Muhlenberg found Clinton up by 9 percentage points and McGinty leading by 5. Now Clinton's lead is down to 3, the survey found, and McGinty has fallen slightly behind Toomey.

The CNN/ORC and Mercyhurst polls also found the presidential race in Pennsylvania within one or two percentage points - statistically even once the margin of error is taken into account.

CNN's poll shows stark differences in the Senate race when it comes to gender and regions of the state.

Among likely voters, McGinty led with women 53-41, while Toomey led with men 51-45.

Toomey had an advantage among independents -- 50-43 -- but McGinty led among moderates, 62-33.

And while McGinty led big in the vote-rich Philadelphia suburbs (51-42) and urban areas (66-29), Toomey had a major advantage in Central Pennsylvania (55-41) and the western part of the state (52-43).

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