WASHINGTON — John McCain carried Kentucky, and Barack Obama countered with a Vermont victory as he bid to become the first black president Tuesday night, first spoils in the race for the White House. Democrats gained a Senate seat, the first of several they had in their sights in a country at war and anything but prosperous.

Interviews with voters suggested that almost six in 10 women were backing Obama, and men leaned his way by a narrow margin. Just over half of whites supported McCain, giving him a slim advantage in a group that President Bush carried overwhelmingly in 2004.

The results of The Associated Press survey were based on a preliminary partial sample of nearly 10,000 voters in Election Day polls and in telephone interviews over the past week for early voters.

The same survey showed the economy was by far the top Election Day issue. Six in 10 voters said so, and none of the other top issues — energy, Iraq, terrorism and health care — was picked by more than one in 10.

The AP made its calls of individual states based on surveys of voters as they left the polls.

The early nationwide popular vote was close. McCain had 52.8 percent, to 46.2 for Obama.

In the Electoral College, where it mattered, Kentucky gave McCain eight and Vermont was good for three for the Democrat.

Obama’s hopes rested on securing the states that John Kerry won in 2004, and picking off other battlegrounds where he waged a costly effort.

Indiana, which last voted Democratic 40 years ago, was one of those, and with votes counted in 8 percent of the precincts, the two men were in a virtual tie.

The Senate seat that switched from Republican to Democrat was in Virginia, where former Gov. Mark Warner won his race to replace retiring Republican John Warner. The two men are not related.