Andrew Johnson was the seventeenth president of the US and followed Lincoln after his assassination. He was a Democrat and as vice president offered a good bridge to the South as the Civil War was ending but as president he was not trusted by the Republicans.
Andrew Johnson pardoned Confederate leaders, allowing them to keep their land and sometimes positions in society. He provided an easy path back into the Union and did not protect blacks from the growing power of groups like the Ku Klux Klan. Johnson vetoed a civil rights act that would have prevented segregation and violence against former slaves. His policies would convince Republicans that they would have to take Reconstruction over in Congress.
This is of course a somewhat subjective question, but most would agree that yes, he was the perfect example of an absolute monarch, since he lived an incredibly lavish lifestyle and allowed for practically no dissent when it came to his grip on power.
The main reason why white northerners were interested in gaining western territory for themselves was because this enabled them to have more power and influence over people of other territories.