A new poll designed to test President Trump’s vulnerabilities on foreign policy heading into the 2020 election finds that economic pain from the China trade war, unraveling alliances and Trump’s relations with Russia are of particular concern to swing voters.Data: Hart Research Associates survey of 1,205 likely voters conduced April 23–27, 2019; Chart: Axios VisualsWhy it matters: The poll was commissioned by National Security Action, a group founded by former top Obama administration officials that is advising Democratic candidates on foreign policy. Jeff Prescott, the group’s executive director, says that while Republicans and incumbents traditionally have an advantage on national security, that's undercut by concerns over Trump’s temperament. He contends that Democrats have “a real opportunity to go on offense” on foreign policy in 2020.The big picture: Trump significantly outperforms his 44% overall approval rating when it comes to national security, on which 55% of all likely voters and 63% of undecided voters approve of his performance.Pollster Geoff Garin says that's in part because voters aren’t paying as much attention to foreign policy as they are to other issues. He says Trump's support dwindles when voters are asked about specific policies and actions.Voters tend to approve of many aspects of Trump’s foreign policy, such as pushing NATO countries to spend more on defense and attempting negotiations with North Korea.However, 46% believe Trump has made America less safe, compared to 38% who say he’s made the country safer. Meanwhile, 57% believe he has made America less respected around the world, while 67% worry he “lacks the temperament we need in a commander in chief.”What to watch: 41% of respondents say Trump’s foreign policy is a reason to re-elect him, 45% say it’s a reason to elect someone else, and 14% say it’s not a consideration.Given a range of foreign policy considerations and asked to select the most important, swing voters prioritize “protecting Americans from terrorism,” “keeping America out of war” and “standing up for American values like human rights and democracy.”Voters trust Democrats more than Republicans to keep the U.S. out of war, work effectively with other countries and defend American values, but trust Republicans more to protect the country from terrorism.The pollsters also tested 20 potential lines of attack against Trump and found that undecided voters were most concerned that Trump was weakening alliances, defending dictators and waging a trade war that will cost jobs and raise prices.The bottom line: Trump fares reasonably well with undecided voters on national security, but that support appears brittle. Prescott says that underlines the need for Democrats to challenge him on these issues in 2020.