LEESBURG, Va. — At a retreat here that has been notable for the improbable exuberance of an energized House Democratic Caucus, President Bill Clinton offered doubt.

Drawing on lessons from his own presidency, Clinton said 2014 poses a more difficult challenge than 2012 and urged lawmakers to tread carefully on the issues of health care, gun control and the economy.

“I can’t tell you how many nights — countless nights in the White House. Every single night before I went to bed for months and months and months after the 1994 election, I thought about the people who were defeated because they voted for the economic plan, I thought about the people who were defeated because they voted for the assault weapons ban. I knew exactly what had happened. And I thought a lot about those who survived and why they did,” Clinton told lawmakers, referring to the 1994 midterm elections that were a GOP landslide.

“I think it’s important to take some action now that it is possible on the issue of gun violence, but it’s important to do it right,” he added.

Clinton said Democrats must have an economic plan to spur growth and said implementation of Obamacare is crucial to ensuring the law becomes popular.

In 2014, Clinton said, it will be more difficult to draw a contrast with Republicans both because there is no presidential campaign to highlight differences and because the GOP is beginning to take smarter approaches on spending battles.

“We should assume going forward that the people who disagree with us honestly on our approach will not make it quite as easy to draw the contrast by the things they do and say as they did last time. As a matter of fact, that’s kind of the message I got out of the House Republican meeting,” Clinton said, noting Republicans’ recent shifts on immigration.

Clinton’s speech topped 40 minutes but kept rapt the audience of House members, who Clinton showered with attention while in office. As Clinton began speaking, a member cried out, “We miss you!” Clinton responded that “sometimes, I miss you, too.”