"Furthermore, I decree that if anyone changes this edict, a beam is to be pulled from his house and he is to be lifted up and impaled on it. And for this crime his house is to be made a pile of rubble. May God, who has caused his Name to dwell there, overthrow any king or people who lifts a hand to change this decree or to destroy this temple in Jerusalem. I Darius have decreed it. Let it be carried out with diligence." NIV translation
The king's order was to be irrevocable and the penalty for interfering with the construction was severe. The king also asked God to overthrow any people that destroys the temple. The temple was destroyed by an army led by Titus (the son of the Roman emperor Vespasian) in the year A.D. 70. Vespasian had been a general under Nero who was the previous emperor. King Darius' decree was implemented as we no longer see a Roman emperor today.
"Then, because of the decree King Darius had sent, Tattenai, governor of Trans-Euphrates, and Shethar-Bozenai and their associates carried it out with diligence." NIV translation
Although the politicians had started out as arrogant in their opposition, they now have changed their position. They are now following the instructions of the king and actually paying the salaries of the men that were rebuilding the temple. Today, many people (even Christian leaders) get hung up on politics and one party or another but, as we see here, most politicians are simply looking out for their own interests.
"So the elders of the Jews continued to build and prosper under the preaching of Haggai the prophet and Zechariah, a descendant of Iddo. They finished building the temple according to the command of the God of Israel and the decrees of Cyrus, Darius and Artaxerxes, kings of Persia. The temple was completed on the third day of the month of Adar, in the sixth year of the reign of King Darius." NIV translation
God spoke to His people through the prophets Haggai and Zechariah. The people obeyed the leading of God and finished the work on the temple. We notice that they prospered as they followed the leading of God and the same thing is true for us today. If we seek God's will and obey when He speaks to our hearts, we will prosper in what we do for the kingdom.