Which of the following was a focus of the new republican party?
supporting irish catholic immigration
encouraging the use of popular sovereignty to determine where slavery could exist
promoting states’ rights
halting the spread of slavery

A focus of the new Republican Party was halting the spread of slavery.

Explanation:

The Republican Party was formed in 1854 by former members of the Whig Party, the Free Soil Party, and some abolitionist Democrats. What all these groups had in common to form the new party was their ideological belonging to the powerful anti-slavery movement, which brought together all white-skinned people in the Northern States of the United States who were fighting to abolish slavery of black people in the southern states of the North American country. They also agreed to promote an economic policy based on two fundamental aspects: a protectionist trade policy, which would diminish or impede imports through high tariffs, to protect the domestic industry from foreign competition; and a policy of "federal improvements", by which the Federal Government had to invest much more money in public works or infrastructure (bridges, roads, etc.) to stimulate the economy.

explanation: we can only guess at how our actions may be perceived in the future. doing something really big like killing lots of people, saving lots of people, affecting the lives of lots of people is a sure fire way of being remembered in historical records. we can also make a difference in the history records by being a small influence on something bigger, whether that is as a civil servant, scientist or artist.

of course you could argue that we all affect history just as tiny cogs in a   bigger machine.

if you mean how do people influence our opinions of things which have already happened, then simply by writing a book which looks at things form a different perspective and trying to convince people that this perspective is more accurate or truthful. people do it all the time i.e. richard the third was a terrible or was he? plenty would disagree, it's just that their views aren't the most widely known.n:

i really do want to but i just don't know it i'm so sorry : (