WHITE PLAINS, N.Y. — For months, Democrats argued that voters would get “serious” about the campaign once it reached the fall and would reject Donald Trump’s no-hold-barred approach.

They’re still waiting.

With fewer than 50 days left, polling shows a tightening national race and – most unnerving to Democrats – a Trump rise in key battleground states. But as Trump’s provocative appeal gains traction, Hillary Clinton is sticking with the traditional playbook: Lots of attack ads, a focus on getting out the vote and intense preparation for the first general election debate, next week.

Her approach underscores what’s emerged as a central question of the 2016 campaign: Can Clinton’s play-it-safe political strategy win against a chaos candidate?

Even President Obama, who long dismissed the idea of a future Trump administration, has started ringing alarm bells, warning Democratic supporters to expect a tight race that Clinton could possibly lose. Polls show the Republican leading in Iowa and Ohio, tied in Florida and North Carolina and gaining in Virginia and New Hampshire.

“This guy is not qualified to be president,” Obama told donors at a Manhattan fundraiser on Sunday. “This should not be a close election, but it will be.”

Clinton’s campaign, Democrats say, has little choice but to stick with its plan. The always-measured Clinton, they argue, can’t out-improvise one of the most unpredictable politicians of the modern era.

“We’re going through the roller-coaster rides of campaigns. All she can do is just keep plowing ahead,” said Steve Schale, a Democratic strategist who ran Obama’s Florida operation in 2008 and advised him in 2012. “She’s going to win it by grinding it out.”

Hoping to calm some supporters’ concerns, Clinton’s campaign sent out a memo Monday, reminding them that the electoral map favors Democrats. The memo charted various paths to 270 electoral votes and urged backers to channel their worry into volunteering.

“Battleground states carry that name for a reason: They’re going to be close, from now until Election Day,” wrote campaign manager Robby Mook. “But we are going to win them because we’ve spent the past year building a superior ground game to communicate our message and turn our people out to vote. So instead of worrying, let’s just get to work!”