Moderate and liberal politicians are
supporting tax cuts. If conservatives continue to dither instead of taking action they will lose their claim to be the champions of lower tax rates.
I've always wondered why liberals (and some moderates) refused to accept the proven track record of supply side (or even just lower tax rates) in stimulating the economy and promoting growth. Whether it was an irrational hatred of all things Reagan (or simply Republican) or being wedded to the idea of controlling people through their pocketbook most non-conservative and non-libertarian politicians seemed happy to let lower tax policies be the domain of their opposition.
No more, it would seem! This would be a severe blow to conservatives hoping to retain some form of a power base. If they lose the people who agree with them fiscally but not on foreign or other domestic policies it will be hard for them to remain a power with the Republican Party, much less the dominant one.