Republican legislative leaders’ difficulties this year in nailing down the details of tax legislation are partly rooted in successes GOP conservatives enjoyed in elections last year.

In August 2012, conservatives unseated top Senate Republicans. They shattered a moderate GOP-Democratic coalition that bedeviled Republican Governor Sam Brownback on issues such as taxes and pensions.

Conservative legislative leaders agree with Brownback’s efforts to follow up on massive individual income tax cuts enacted last year with another round of cuts. They don’t seem far apart on adjusting the sales tax to stabilize the budget.

Yet their impasse on the sales tax is dragging out the Legislature’s session.

Shattering the Senate’s old governing coalition eliminated a political foil for conservative Republicans in both chambers that had kept them pursuing the same policy goals.