Two conservative groups that split over the Republican Obamacare replacement plan called Thursday for a united front on tax reform, despite the early prospects of division caused by the House Republican plan.

The push for tax reform will fail if advocates do not join forces, National Taxpayers Union Vice President Brandon Arnold said Thursday, in the latest round of positioning over taxes.

"If we're going to get it done, we can't have the same level of division in our ranks," Arnold told reporters Thursday. "We have to unify on this issue and that's what we're trying to do."

Arnold said his group and Freedomworks, a libertarian group that opposed the Republican healthcare plan that the National Taxpayers Union supported, has joined forces on the issue, including by publishing an op-ed Thursday praising the House Republican tax reform blueprint.

The Paul Ryan-backed House legislation has divided outside conservative groups because of one provision in particular, a border-adjusted corporate tax. President Trump has not taken a side.

Some right-leaning groups, including the Koch-backed Americans for Prosperity, have staked out aggressive opposition to the border adjustment feature, which they warn would raise prices on importers and consequently consumers.

Arnold said Thursday that "we need to reset the debate" over the House GOP proposal, focusing not on arcane provisions but on the overall result that it would simplify and lower taxes, boosting take-home pay.

As for the opposition to border adjustment, Arnold suggested that if it is to remain in the legislation, congressional leaders need to do more to educate the public about how it works and provide transition rules for businesses worried by it.

Even though Republicans control the White House and Congress, tax reform won't happen without consistent outside support, National Taxpayers Union President Pete Sepp said.