No the Dems want amnesty because they will be future Democrat voters. The GOPe wants amnesty to please their corporate paymasters by keeping the free flow of cheap, exploitable labor going to enhance their bottom line.
87% of the 1.1 million LEGAL IMMIGRANTS we bring in each year are minorities as defined by the USG. And almost all of the illegal aliens are minorities. Immigrants and minorities vote more than two to one Dem. In 2012 whites voted 59%-39% for Romney. White women voted 56% to 42% for Romney. 96% of blacks, 73% of Asians, and 71% of Hispanics voted for Obama. Minorities currently make up about 37% of the voters. That will only increase.
By 2019 half of the children 18 and under will be minorities as defined by the USG. As a result, each cohort that turns 18 annually will be more Democrat than the previous one. The status quo on immigration even without amnesty will guarantee that the Dems will be the permanent majority party. Demography is destiny.