Final NYT/Siena polls: Democrats ahead in all 7 Senate battlegrounds. Our read on the samples

The final New York Times/Siena polls of likely voters, taken Oct. 23 to Nov. 1, show Democratic Senate candidates ahead in seven states: Michigan (El-Sayed 53%, Rogers 42%), Texas (Talarico 50%, Paxton 43%), Maine (Jackson 51%, Collins 45%), Ohio (Brown 49%, Husted 44%), Kansas (Hamilton 49%, Marshall 44%), Alaska (Peltola 48%, Sullivan 46%) and Iowa (Turek 48%, Hinson 47%).

Siena's Don Levy called a blue wave "a distinct possibility" but said that with so many races inside the margin of error, "a Senate majority for either party remains possible." Margins of error run from 3.4 points in Texas to 5.0 in Alaska. Forecaster Nate Silver wrote that polls have "crossed the threshold" of projecting a Democratic Senate.