Washington ? President Barack Obama has tried to hold off debate on contentious social issues such as abortion, immigration and gay rights as he focuses on the economy and the wars in Iraq and Afghanistan. The Supreme Court vacancy will make that harder to do.

Political battles over new justices tend to center on those types of social issues far more than on economic and foreign affairs, which have dominated the opening months of Obama’s administration.

Some liberals have criticized Obama for postponing efforts to revamp immigration laws, protect access to abortion, and allow gays to serve openly in the military. The president has taken the heat from his political base, hoping to avoid getting bogged down on a volatile issue early in his term, as President Bill Clinton did on the question of gays in the military.

The strategy has worked so far. Even the grumbling liberals are, on balance, happy to have Obama in the White House after eight years of George W. Bush. And the nation’s economic distress has preoccupied Congress and the general public.

But the process to replace retiring Supreme Court Justice David Souter could pump new oxygen into national debates over abortion, immigration, minority rights, limits to privacy and other matters that often animate large grassroots organizations, which have been comparatively quiet in recent months.

“There’s no doubt these debates are coming back,” said Matt Bennett, vice president of the centrist Democratic group Third Way. They might create more noise than suspense, he said, because there is little doubt that the Democratic-dominated Senate will confirm Obama’s eventual choice. Liberal activists will “fall in line” even if they are not entirely satisfied with administration’s progress on their pet issues, Bennett said.

Obama has tried to push several of these social issues to the political background. At his news conference Wednesday, he said a bill important to abortion-rights advocates is not his highest priority. Access to abortion must be protected, he said, but “the most important thing we can do to tamp down some of the anger surrounding this issue is to focus on those areas that we can agree on.”

He was similarly noncommittal on immigration, which his aides see as one of the most difficult and emotional political issues around. As a candidate, Obama said the nation must devise a way to help millions of illegal immigrants achieve legal status if they follow certain guidelines. But he has been mostly silent on the subject since his election. On Wednesday, he suggested he’s at the mercy of a slow-moving Congress, which has proven unable to agree about immigration for years.

“Ultimately, I don’t have control of the legislative calendar,” Obama said, “and so we’re going to work with legislative leaders to see what we can do.”

A Supreme Court nomination process threatens to amplify criticisms of Obama from liberals. Relatively few have added their voices so far to critics from the right. But those who have spoken out are likely to get more attention, and perhaps more support.