How much American anti-immigration sentiment was due to bigotry, and how much due to to economic fears? Since that covers a few centuries and many immigrant groups, for the sake of discussion let's narrow it down to the Irish (not Scotch-Irish), especially during the peak Irish immigration era of the 1840's and 1850's. However, discussion of any other group or time period is also more than welcome.

By bigotry I mean hating people solely due to their ancestry, culture, etc. By economic fears I mean hating or disliking, or at least opposing immigration because of a fear that it will lower wages and increase unemployment.

As for bigotry, I might be guilty of a little presentism, but I think the Irish would be the least "foreign" immigrants to the English, Scotch-Irish, etc. that were already here. Their culture is very similar, or at least more similar than other immigrants groups, and many or most Irish spoke English. I'd think that alone would make them less foreign than say German immigrants, of which there had already been many. I suppose the Irish being Catholic would be the biggest problem. What about Germans though? Coming from a country that's roughly half Protestant and half Catholic, weren't many of them Catholic?

As for the economic fears, before anyone can write "lump of labor fallacy", I'll make an argument that the economic fears may have been legitimate. The lump of labor fallacy says that there is only so much work to be done, so more people means lower wages and higher unemployment. Obviously that's a fallacy in the long run, but the short run may be a different story. There was a certain mix of rich, middle class and poor people in the US (obviously I'm simplifying for clarity) but almost all the Irish were poor. More poor people would be good for the rich factory owner who wanted to hire more employees, or the middle class person who wanted to hire a maid, because they'd work for less. It would be bad for poor people for the same reason though. Also, while more people means more demand, and hence more work, the poor don't demand much (because they can't afford it) compared to the rich and middle class.

Moreover, even if my economic reasoning is wrong, the most important thing here is what people expected the economic effect to be.

I realize that economic fear may lead to bigotry, making the two difficult to untangle. I also realize precise answers to this question are impossible. However, I'd be interested in any historical work that showed which factors were more or less important.