President Donald Trump is seeking to withhold more than $800 million in federal spending that Congress has already approved, opening another dispute between the White House and lawmakers over control of government funding.

The administration announced the move on Friday, targeting programs involving immigration, education, refugee assistance, minority business development and overseas conservation. The White House said it was using available tools to reduce spending on programs it considers wasteful or harmful.

The administration is using a rarely applied mechanism known as a “pocket rescission,” which allows the executive branch to seek cancellation of appropriated funds without going through the normal congressional rescission process.

The move has drawn opposition from lawmakers. Senator Susan Collins, the Republican chair of the Senate Appropriations Committee, called the action illegal, arguing that Congress has constitutional authority over federal spending.

The dispute comes as Washington continues to debate the balance of presidential spending authority and Congress’s power of the purse. The Supreme Court previously declined to block the Trump administration from using the same mechanism to withhold billions of dollars in foreign aid while litigation continued.

The latest funding dispute could lead to further legal and congressional challenges as lawmakers examine the administration’s authority to withhold the approved funds.