HOUSTON -- U.S. Rep. Ron Paul, a strict constitutionalist and fierce anti-war critic, will formally declare his candidacy for the Republican presidential nomination Monday when he appears as a guest on a C-SPAN call-in program.

Paul, R-Texas, created a presidential exploratory committee in January, allowing him to begin collecting money on behalf of his bid. Kent Snyder, the chairman of that committee, said Saturday that Paul would make his candidacy official on Monday.

This will be Paul's second try for the White House. He was the Libertarian nominee for president in 1988.

Snyder said Paul is scheduled to be a guest on "Washington Journal" Monday morning and will make his announcement then.

Paul, a nine-term congressman who represents a district just south of Houston that includes Galveston and stretches along the Gulf Coast nearly to Corpus Christi, describes himself as a lifelong Libertarian running as a Republican.

Paul has spent most of his career outside the GOPs traditional circles. He limits his view of the role of the federal government to those specifically laid out in the U.S. Constitution. As a result, he sometimes casts votes that appear at odds with his constituents and other Republicans.

Paul, for example, was the only Republican congressman to vote against Department of Defense appropriations for fiscal year 2007, which he opposed because of the war in Iraq -- a war he says is "not necessary for our actual security."

He once described President Bush as "not a constitutional president" and voted against a resolution declaring that the United States would win the war on terror.

He acknowledges that the national Republican Party has largely shunned him despite his nine terms in office under its banner. He gets little money from the GOP's large traditional donors, but benefits from individual conservative and Libertarian donors outside Texas.

Paul bills himself as "The Taxpayers' Best Friend," and is routinely ranked either first or second in the House of Representatives by the National Taxpayers Union, a national group advocating low taxes and limited government.