Martial law would not be "declared" under President Mrs Bill nor would electioins be cancelled. Martial Law would be imposed piecemeal and gradually and would be bureaucratically run rule with federal police backup and small military units. The professional uniformed Military is always distrusted and feared by leftists of all degrees and nomenclature. The USSR had two separate armies, one of them to check coup possibilities of each other as well as having commissars in every unit with the authority to shoot troops and commanders at all levels. And in the end, the military did betray the Communists.
Iran keeps its normal Military half in the closet and as backup in case of actual invasion. All its internal and external warfare and suppression is carried out by quasi military thugs. It is thus with all left, moslem and other totalist ideologies.
Elections are necessary in totalist societies to "legitimize" the regimes internally and to other countries. Elections in such states are absolutely controlled and outcomes preordained but the elections must be held.
You nailed it.
Plus, with 400-600 million guns in the country, even the most successful confiscation would still leave 10-20 million, so they would need the fig leaf of elections to legitimize their power.