U.S. President Donald Trump's first budget proposal will spare big social welfare programs such as Social Security and Medicare from any cuts, Treasury Secretary Steven Mnuchin said in an interview broadcast on Sunday.

Mnuchin said Trump would also use a major policy speech to a joint session of Congress on Tuesday night to preview some elements of his sweeping plans to cut taxes for the middle class, simplify the tax system and make American companies more globally competitive with lower rates and changes to encourage U.S. manufacturing.

Speaking on Fox News Channel's "Sunday Morning Futures" program, Mnuchin, who has acknowledged that tax reform is his top policy priority, said the budget plan would not seek cuts to federal benefits programs known as "entitlements."