Walker is currently the clear frontrunner in the Republican primary in 2016 according to most polls—
check this out:

Wisconsin Gov. Scott Walker told Breitbart News in an exclusive interview over Memorial Day weekend that he’s getting much closer to a decision on whether he’ll pursue a presidential campaign in 2016, a decision he expects will come in early July.

“My state budget is done at the end of June, and so obviously my number one responsibility over that period is to complete a state budget—and so I’ve said in state and publicly that I won’t make any declaration about my intentions until after that,” Walker said when asked where he’s at in his decision-making process.