The reasons the United States wrote and proposed the declaration of independence is listed in the main body, located by the grievances. However, in summary, Enlightenment thinkers such as John Locke, Voltaire, and Montesquieu gave people light and hope of their own self worth. England was raising major taxes and trampling on the human rights, proposed by John Locke. Overall, England was raising major taxes, and treating the colonies unfairly.
Massive amounts of loans given and not enough money to pay it back
Answer:
It's because the party that's not in office is usually more angry about what's currently going on in politics, and they want to vote to change that.
For example, the Democrats gained a bunch of seats during the midterms, because they don't like what Trump is doing in office right now, and they wanted to vote to have more representation. The same thing happened when Obama was in office from 2008-2016. The Republicans gained more seats, because they didn't approve of Obama and wanted change.