Is voting a fundamental right?

Congress seems to think so.

The Supreme Court might disagree.

From Title 52-VOTING AND ELECTIONS: 

The Congress finds that-

(1) the right of citizens of the United States to vote is a fundamental right;

(2) it is the duty of the Federal, State, and local governments to promote the exercise of that right; and

(3) discriminatory and unfair registration laws and procedures can have a direct and damaging effect on voter participation in elections for Federal office and disproportionately harm voter participation by various groups, including racial minorities.