The extreme right and the extreme left both have a penchant for lawlessness that fuels violence and terrorism. It is ahistorical to identify such terrorism only with either the hard right or the hard left, though partisans always seem to do that when it serves their own ideological interests. The hard right and the hard left share a distrust of dialogue, an intolerance toward those with whom they disagree, and a willingness to use despicable means to achieve what they believe are desirable ends.
All Americans should condemn terrorism, regardless of its source, but conservatives have a special obligation to condemn right wing terrorism, just as liberals have a special obligation to condemn left wing terrorism. No one should be given a pass. It is not that conservatives are responsible for right wing terrorism or that liberals are responsible for left wing terrorism. The point is that right wing terrorists often falsely claim to be acting on behalf of the conservative agenda. Similarly, left wing terrorists sometimes falsely claim to be acting on behalf of the liberal agenda. It is too easy for conservatives and liberals to condemn the other side.
Both sides have to disassociate themselves from violence on their side of the political spectrum.