Dems pull TV ads in Kentucky

• The DSCC has gone dark in Kentucky's Senate race


• The move means Alison Lundergan Grimes is largely on her own against GOP Sen. Mitch McConnell


• Democrats are focusing their resources on endangered incumbents

Washington (CNN) -- Democrats pulled their TV advertising in Kentucky from now through election day, leaving Senate hopeful Alison Lundergan Grimes without air support from the national party, which had invested heavily in trying to unseat the Senate's top Republican.

It's a sign of how stretched Democrats are in defending their own turf across the country that they can no longer afford to go on offense in the marquee race against Senate Minority Leader Mitch McConnell.

But Grimes sources insist they'll be fine on their own. The campaign, sources said, is flush with $4.4 million cash on hand -- much more than other Democrats on the ballot this year.

High-stakes debate in Kentucky

"Money is not an issue in this campaign," a Grimes source said.

While the Democratic Senatorial Campaign Committee is coming off the air, national Democrats are still likely to spend money on the ground in Kentucky before election day to help boost Grimes' get out the vote operation.

"We continue to make targeted investments on the ground and will continue to assess the race to decide on future television buys," a Democratic source with knowledge of the DSCC's strategy told CNN.

The move comes as Democrats focus their resources on defending the party's endangered incumbents. Senators like Alaska's Mark Begich, Arkansas' Mark Pryor, Colorado's Mark Udall, Louisiana's Mary Landrieu and New Hampshire's Jeanne Shaheen are all fighting for survival -- and to keep the GOP from winning the six seats it needs to capture the chamber's majority.

Grimes has been under fire for twice in the last week -- first in an editorial board meeting, and then in a debate with McConnell -- dodging questions about whether she voted for President Barack Obama -- which led NBC's "Meet the Press" moderator Chuck Todd to say that the Democratic secretary of state had "disqualified herself," and Republicans to immediately place that comment in a TV ad.

A Grimes source said that question had come up in debate prep, and she answered it the same way she did during Monday night's debate, saying that as the state's chief election officer, the privacy of the ballot box is "a point of principle with her."

The source said Grimes' campaign hasn't polled on how the fallout over her refusal to disclose how she voted has affected the race, but sees it as a national media-fueled issue.

"The people of Kentucky accept her explanation," the source said, adding that "not one person has come up to her to say she needs to divulge" how she's voted.

CNN Chief Political Analyst Gloria Borger contributed to this report.