WASHINGTON (AP) — The U.S. Senate race in Kentucky looks as if it could stand as the model for what looks increasingly likely to be the Democratic Party's failed battle to fend off the Republican bid to take control of Senate in midterm elections next month.

Republicans need a net gain of six seats to take control of the Senate in the Nov. 4 election. Success there, coupled with the party's already big and unassailable majority in the House of Representatives, would crush President Barack Obama's legislative agenda in his final two years in the White House.

In Kentucky, Democrats hoped they had a winner in Alison Lundergan Grimes in the contest to unseat Senate Minority Leader Mitch McConnell, an Obama nemesis who is in line to take over as the powerful majority leader post if he wins a new term and Republicans take control of the chamber. Grimes was seen as a strong candidate given her work as Kentucky secretary of state and McConnell's unpopularity in the state.

But national Democrat organizations have just pulled out of television-ad spending in support of Grimes, who is trailing McConnell by just a few percentage points in polls. That coincided with the brouhaha over Grimes' refusal to answer questions about whether she voted for Obama in 2008 and 2012.

Grimes' refusal to say if she voted for Obama reflects the big drag the president is having on some Democrat Senate candidates, who have shunned Obama campaign appearances on their behalf, hoping to distance themselves from their unpopular leader. Obama's approval ratings ticked down to 40 percent, the lowest level of his six years as president, according to a new ABC News-Washington Post poll.

On Wednesday, Obama postponed planned campaign trips to New Jersey and Connecticut to focus on the federal response to Ebola.

With McConnell looking increasingly safe, Democrats also appear to have ceded two of their open seats in Montana and West Virginia. They are also facing the possible loss of Democratic seats in Louisiana, Arkansas and Alaska.

Democrats still hope for relief in Kansas, where long-time conservative Republican Sen. Pat Roberts has only a small polling advantage over Independent Greg Orman. But Orman has not said whether he would vote with Democrats or Republicans. And if he hopes for re-election in 2020 in deeply conservative Kansas, political reality may see him side with the Republicans.

Democrats also still hope to gain a seat in Georgia, where Michelle Nunn, daughter of very popular former Sen. Sam Nunn, is within a few points of businessman David Perdue. And in Republican South Dakota, a potential upset is in the works. Former Republican Sen. Larry Pressler, who now is Democrat-friendly, is gaining ground on former Republican Gov. Mike Rounds. That race is further complicated by good but trailing poll numbers for Democrat Rick Weiland.

The open Democrat seat in Iowa looks increasingly likely to be going to Republican Joni Ernst. And in Colorado, polls are trending toward Republican challenger Cory Gardner over incumbent Democrat Sen. Mark Udall.

So, leaving aside possible potential Democratic upsets in South Dakota and Georgia, the Republicans would gain six seats, one more than the number needed for majority control. Should things go against Republicans in Georgia, Kansas and South Dakota, that would cut their pick-up to five, one short of the majority. Should the outcome split 50-50, that would give the tie-breaking vote to Vice President Joe Biden, leaving the Democrats with nominal control.

Although Republicans chances of taking the Senate look better than that 50 percent, polls can be wrong and voter certainty nearly three weeks before Voting Day can be fickle. At the same time, the fact that this election falls in the sixth year of a presidential term, voting history favors Republican ascendance. The party that controls the White House in such elections historically has lost considerable ground in Congress.