Beginning with the 21st VNO Mass, we look to various “Civil Needs.” Some of them have no proper antiphons assigned, Masses for the nation or state (#21), for those in public office (#22), for a governing assembly (#23), or for the head of state or ruler (#24). For clergy prayers, each of these contains a lonely collect. Perhaps the intention here is to use the prayer itself on some civic occasion, such as the swearing in of politicians.
These government issues are covered very well in the Lectionary for Mass, however. Numbers 882-886 actually give a large number of readings, on par with the number of choices for a wedding or funeral. Felix Just’s Lectionary site has the full summary of VNO Masses here. Just be aware that “themes” don’t exactly match what’s in the 2010 edition of the roman Missal in English.
If you were to ask me my perfect choices for a special Mass for the government in today’s American climate, I’d use Isaiah 58:6-11 (authentic fasting), then Advent’s Psalm 85 (more on justice and peace in the governance of God), followed by the Gospel of the Last Judgment (Matthew 25:31-46).
If I were looking to a Psalm for another musical text, I’d say the 112th fits well.
Some years ago, we blogged on Masses And Prayers For Various Needs And Occasions. In the GIRM, sections 368-378 cover the universal regulations on their use. You can check our brief comments here and here and here. The USCCB’s unannotated text on the matter is here.