Senator Marco Rubio's strong conservative credentials could make him a driving force in the immigration debate, if he chooses.

In his first two years in the Senate, the Florida Republican rolled up a perfect voting record, as measured by the American Conservative Union. He was one of only four senators to score that high on the ACU scorecard in 2011 and 2012.

He has consistently sided with social conservatives. He is unswervingly anti-abortion and has opposed government support for stem-cell research. He is among a handful of senators who have threatened to filibuster any gun-control measure that comes to the floor. He is against gay marriage. In an interview last year, he said he wasn't sure whether evolution or creationism was more credible.

On foreign policy, he strongly supports Israel and is a hardliner when it comes to Iran's nuclear program. He opposes a timetable for withdrawing U.S. troops from Afghanistan and is a defense hawk. The lawmaker, whose parents left Cuba before Fidel Castro took power, is a leading critic of that communist government.

As a candidate and now as a senator, he has favored repealing President Barack Obama's Affordable Health Care Act, and has endorsed a constitutional amendment mandating a balanced budget.

Rubio wanted to extend all the tax cuts enacted under President George W. Bush, including those for upper-income Americans; he lost that battle in January. He wants to slash taxes for business and wealthier investors, by cutting the corporate tax rate and eliminating all taxes on capital gains, dividends, interest and estates.

This would cost hundreds of billions in revenue. He hasn't specified how he would pay for the tax cuts and also achieve a balanced budget.

(Albert R. Hunt is a Bloomberg View columnist. E-mail him at ahunt1@bloomberg.net or follow him on Twitter.)