Blessing on a King

There is a special blessing recited upon seeing a king: "she-nasan mi-khvodo li-vsar va-dam". Is that recited upon seeing the president of a democratically elected government?

The Mishnah Berurah (224:12) writes that one recites the blessing over a ruler who is not a king but does not have a king over him and can have someone executed. One would think that since a president cannot have someone executed, he does not merit a blessing. However, many recent posekim have ruled that if he can pardon a criminal then he is considered to have life-and-death powers and merits a blessing. These include R. Ovadiah Yosef (Yechaveh Da'as 2:28), the Minchas Elazar (5:7), and R. Shlomo Zalman Braun (She'arim Metzuyanim Ba-Halakhah 60:6).

The reason offered for reciting this blessing is that the respect given to a king today will pale in comparison to the respect given to the king mashi'ach. Therefore, one should make an effort to see a king and the respect accorded to him and recite the blessing, so the contrast in the future era will be fully recognized.

Based on this reason, the posekim above add that the blessing only applies to a ruler who wears special royal clothes and travels with a retinue. Wearing a regular civilian suit and traveling with bodyguards does not count. Therefore, most presidents today do not qualify for the blessing.