At home and abroad, President Biden is confronting what it means to lead a changing Democratic Party.

The center of gravity in the party still seems closer to Biden’s center-left than to Sen. Bernie Sanders’s democratic-socialist left, as Biden’s victory in the 2020 nomination battle confirmed. In primary campaigns in competitive districts, voters have often supported a more moderate candidate over a more liberal one.

Yet everyone agrees that Democrats have moved left since Biden served as Barack Obama’s vice president. The liberal wing’s influence has grown, and what power it has is amplified through social media and cable TV. As president, Biden feels the changes constantly.

They were evident throughout the 11-day conflict between Israel and Hamas militants in the Gaza Strip. Biden and his advisers had to weigh traditional U.S. support for Israel’s right to defend itself against Hamas-launched rocket attacks with rising concerns — particularly but not exclusively among those on the Democratic left — over the number of casualties as well as the widespread destruction in Gaza by the Israeli military.

Biden’s support for Israel over many years has been unwavering. He reiterated that position Friday. “There is no shift in my commitment to the security of Israel. Period. No shift, not at all,” he said. “But I’ll tell you what there is a shift in: We need a two-state solution. It is the only answer.”

Through mostly quiet diplomacy, along with one unusually public demand to Israeli Prime Minister Benjamin Netanyahu to de-escalate, the Biden administration helped to bring about an Egyptian-brokered cease-fire, fragile as it may be. That public shove to de-escalate was indicative of the new political environment, and it appeared to help bring about results.

In remarks Thursday evening, after the cease-fire was announced, Biden had reiterated U.S. support for Israel, promising to replenish Israel’s Iron Dome defense system. He also pledged to work through the United Nations to provide humanitarian assistance and reconstruction funding for the people of Gaza. He said the United States would work with the Palestinian Authority, not Hamas, in these efforts “in a manner that does not permit Hamas to simply restock its military authority.”

Two days earlier, Biden had praised Rep. Rashida Tlaib (D-Mich.), a Palestinian American who has been scorching in her criticism of Israel. Biden and Tlaib had a vigorous conversation on an airport tarmac when he arrived in Michigan. Shortly after, he said publicly how much he admired Tlaib’s intellect, passion and concern for others, adding, “And God, thank you for being a fighter.”

That was acknowledgment that, if Biden has not shifted, the backdrop against which this conflict took place was different than in the past, especially among Democrats. “There’s still strong support for Israel in the Democratic Party,” said a former Obama administration official, who spoke on the condition of anonymity to offer candid analysis. “But the dynamics have become more complicated.”

Netanyahu’s choices to align himself with former president Donald Trump and the Republican Party, and Trump’s policies, which did not offer even the pretense of evenhandedness, contributed to turning what had been strong bipartisan support in the United States for Israel into a more combustible partisan environment. Which in turn has led more Democrats to become sympathetic to the Palestinian people and less supportive of Israel.

A February Gallup survey found that 75 percent of Americans said they had a positive view of America’s closest ally in the Middle East, and those numbers have been relatively stable. Meanwhile, since 2018, favorable views of the Palestinian Authority have risen from 21 percent to 30 percent. Among Democrats, favorable views rose from 26 percent to 38 percent.

A decade ago, by margins of about 2-to-1, Democrats said their sympathies were more with Israelis than with Palestinian Arabs. Polling in February showed Democrats now closely divided, with 42 percent saying their sympathies were with Israelis and 39 percent citing the Palestinian Arabs. That compares with a 79 percent to 11 percent split in favor of Israelis among Republicans.

On a key question of whether the United States should put more pressure on Israelis or Palestinians to resolve conflict, many Democrats have turned against Israel. Gallup’s 2021 survey found 50 percent of Democrats saying they thought Israelis should be pressured more, compared with 30 percent saying the pressure should be applied more to Palestinians.

Some Democratic lawmakers are criticizing Israel’s actions against Hamas, while others are following President Biden in saying it has a right to defend itself. (JM Rieger/The Washington Post)

Biden is dealing with similar changes within his party on domestic issues. He has proposed an agenda that in size and ambition is a reflection of the kind of government activism Sanders has been pushing for years, and one not seen since the presidencies of Lyndon B. Johnson or Franklin D. Roosevelt.

The American Rescue Plan, American Jobs Plan and American Families Plan would cost, if fully enacted, around $6 trillion. The Rescue Plan became law earlier, and the current focus now is on the infrastructure package, which Biden has redefined to include programs that would include not an ounce of asphalt nor a single steel girder.

Biden’s trio of proposals obviously will not be enacted in full. The president has told Republicans he’s prepared to scale back the infrastructure package in the hope of gaining some bipartisan support. Republicans on Friday said the two sides are still far apart after efforts at negotiation. That leaves Biden with the decision of whether to keep negotiating or move ahead without Republicans, as many liberals advocate.

The president maintains he has not really gone far left. “The progressives don’t like me because I’m not prepared to take on what I would say and they would say is a socialist agenda,” he told New York Times columnist David Brooks. What he means is he won’t support a Medicare-for-all plan that Sanders favors. Nor will he embrace calls to defund the police, as some in the Black Lives Matter movement advocate.

That doesn’t mean he hasn’t been influenced by what the left has been advocating. He explains the size of his domestic agenda as necessary to show that democratic governance can do a better job for people than authoritarian government, or to show that the world should look to the United States rather than China for leadership globally.

Would he say these things had not the left wing of the Democratic Party championed a more ambitious and aggressive role for government and persuaded many rank-and-file Democrats to agree? The pandemic created needs for stepped-up government action that might have been ignored in the past. The party’s left provided the energy and incentive for the president to go big.

Biden will have to make some difficult choices about the unfinished parts of his economic and domestic agenda. He will continue to feel pressure from the left on voting rights, immigration, racial injustice, guns and the filibuster. So far he has maneuvered through this with relative confidence, but he has been forced by circumstances to adapt to the changes within his party and govern accordingly.