Because on the surface it seems as if Republican and conservative values align more with Torah values than Democratic and liberal ones.
In reality, they are all apikorsim whose only values lie in tayva. Look at the Great and Might Trump, for example. Is this menuval really supposed to be the pinnacle of what a Jew should vote for just because he made some token gestures about Israel? Also I find it extremely ironic that those who benefit the most from liberal social programs like Medicare, FAFSA, Section 8, and WIC are the ones that vote overwhelmingly Republican.
Democrats are bad. Republicans are bad. As a klal we need to start looking more objectively at politics and decide to support those that are slightly less damaging in their policies.