Secretary of State Mike Pompeo, left, shakes hands with Rep. Eliot L. Engel (N.Y.), the top Democrat on the House Foreign Affairs Committee. (Leah Millis/Reuters)

Democrats critical of President Trump’s foreign policy say they plan to use their House majority to take a closer look at his private conversations with world leaders, overseas business entanglements and the purge of diplomats from the State Department.

Even before Tuesday’s election handed control of the House to Democrats, lawmakers who have been shut out of the debate for two years began compiling an ambitious list of issues they hope to tackle when they take charge in January. The lengthy lineup reflects two frustrating years for Democrats who have repeatedly sent letters imploring the White House to answer their questions, to no avail.

Trump has said he would adopt a “warlike posture” if Democrats on several committees in the House forge ahead with plans to investigate him and his administration. A Democratic aide replied that the Foreign Affairs Committee would do its job and exercise its oversight authority, “one way or another.”

To a large degree, oversight on foreign policy presents Democrats with as many limitations as responsibilities. The executive branch runs foreign policy, while Congress controls the purse strings.

What a Democratic-controlled House can do is set the stage for 2020, making the case that Democrats are better at foreign policy and national security than Republicans.

“It's all about framing for 2020,” said Joel Rubin, who was the State Department’s liaison to the House during the Obama administration. “So much of what the House can do is not through writing a bill that will have to be agreed to by the Senate and signed by the president. It’s about clarifying differences and highlighting them.”

The Democrats’ wish list includes hearings advancing alternatives to White House policies on climate change, refugees and migration, according to a Democratic aide, speaking on the condition of anonymity to discuss the plans more frankly.

They want to find out what Trump said to Russian President Vladi­mir Putin at a July meeting in Helsinki unattended by any White House aides, and what he told North Korea’s Kim Jong Un when they met with only interpreters present during a June summit in Singapore. They intend to explore his business relationships in foreign countries and possible conflicts of interest with Russians.

They have oversight responsibility over the State Department and plan to use it by delving into whether dozens of career diplomats have been pushed out because they were not considered Trump loyalists.

Several committee members have articulated tougher positions than the White House on Russia, North Korea and Saudi Arabia and urged congressional authorization on military engagement in hot spots such as Syria.

“It’s a long agenda,” the Democratic aide said.

Many of the issues already have been put forward by Rep. Eliot L. Engel (N.Y.), the top Democrat on the Foreign Affairs Committee.

As the ranking Democrat, Engel has issued a steady stream of barbed commentary over Trump’s policies — among them, withdrawing from the nuclear deal with Iran and weapons treaties with Russia, threatening to withhold aid to several Central American countries, slashing refu­gee admissions and support for the Saudi-led war in Yemen.

But there is little the Engel-led committee could do to reverse some policy decisions, including the U.S. pullout from the nuclear deal with Iran and hundreds of sanctions measures.

Foreign assistance enjoys bipartisan support, and Congress has already rejected two sizable budget cuts proposed by the Trump administration.

The ability for Democrats to make their voices heard on foreign policy may be the most potent weapon they have.

“There’s going to be a lot of noise, a lot of heat and a lot of light shed on Trump’s foreign policy,” said Aaron David Miller, a former State Department official who is a scholar at the Wilson Center. “The real question is how consequential it is going to be. On foreign policy, the administration has tremendous advantages by virtue of what the Constitution says.”

Miller said any Democratic emphasis on the administration’s perceived foreign policy failures is likely to fade away as domestic concerns rise to the fore. For example, he said, few will focus on foreign policy if special counsel Robert S. Mueller III does not get fired in the three months before the new Congress begins, and he hands in a report raising questions about Russian influence in the Trump campaign.

“If it’s not the Mueller report, the focus will be redistricting or campaign finance reform,” he said. “They have to identify discrete issues on which to focus. And they have limited bandwidth to make real dents in the administration’s strategy.”