WASHINGTON (AP) — Conservatives wait warily as President Bush makes final decisions about his election-year budget, three years into an administration on whose watch spending has mushroomed by 23.7 percent, the fastest pace in a decade.

While Bush has emphasized repeatedly the need to rein in spending, overall federal expenditures have grown to an estimated $2.31 trillion for the budget year that started Oct. 1. That is up from $1.86 trillion in President Clinton’s final year, a rate of growth not seen for any three-year period since 1989 to 1991.

Much of the increase stems from the fight against terrorism and wars in Afghanistan and Iraq. Also expanding relentlessly have been huge programs such as Social Security, Medicare and Medicaid, which grow automatically with inflation, higher medical costs and more beneficiaries.

What has vexed conservatives most is the 31.5 percent growth in discretionary spending since Bush took office. That is the one-third of the budget lawmakers approve annually for defense, domestic security, school aid and everything else except Social Security and other benefits.

Such spending grew by an annual average of 3.4 percent during Clinton’s eight years.

Further infuriating conservatives, Bush and the Republican-run Congress have enacted a $400 billion, 10-year enlargement of Medicare; $87 billion in expanded benefits for farmers; and $40 billion for increased veterans’ payments and the Air Force’s leasing and buying of refueling tankers.