MANCHESTER, N.H. — The third Democratic presidential debate opened with an apology and ended with compliments.

For months, the Democratic primary contest has been a relatively civil affair – offering a tone that party leaders see as a much-needed contrast to the raucous Republican field.

A day after a rancorous dispute over a breach of private campaign data by Vermont Sen. Bernie Sanders’ campaign roiled the Democratic Party, a political truce between Hillary Clinton and Sanders largely held – even as Sanders’ aides seemed itching for a more aggressive confrontation with the front-runner.

“I apologize to Secretary Clinton,” said Sanders. “This is not the type of campaign that we run.”

Mindful of the grassroots support she’ll need to fuel a general election bid should she capture the nomination, Clinton accepted his apology, instead, keeping her criticism carefully aimed at her GOP rivals – particularly businessman Donald Trump.

“I’m very clear that we have a distinct difference between those of us on this stage tonight and all of our Republican counterparts,” she said, in her opening remarks. “We have to prevent the Republicans from rolling back the progress that we’ve made.”

Clinton’s brush-off of the data breach controversy underscores her confidence in a race in which Sanders is struggling to regain momentum as it shifts away from an economic message – the core of his campaign – to one over national security, because of terrorist attacks in Paris and San Bernardino, California.

Sanders’ pledge to avoid personal attacks has seemed to frustrate his aides at times, who have occasionally gone on the offensive on their own – earlier this month, they pulled ads linking Clinton to Wall Street.

The Sanders campaign’s handling of the data breach this week emphasized the apparent disconnect between the candidate and his staff. His aides came out swinging on Friday after revelations that their staffers stole some of Clinton’s voter data, using a clumsy response by the Democratic National Committee to charge party leaders with favoritism and insinuate that her campaign also lifted some of their information.

Sanders did not follow their lead. Instead, he chose to forgo the political opportunity, just as he did in the first debate when he dismissed controversy over Clinton’s use of a private email server as secretary of state.

Clinton has moved quickly to touting her experience as secretary of state and casting herself as an experienced hand in a dangerous world – an argument her aides believe will play well against both Sanders and non-establishment GOP contenders like Trump.