As I have posted in the past, there is a demographic change happening to the United States population. The Hispanic portion of the population is growing much faster than any other portion. That means that sometime fairly soon Whites will be the minority in this country -- and indeed, that is already happening in some states like Texas, where Whites are already a minority in the state's school system.
The Republicans know that this change will eventually spell doom for their party -- because of their racist, anti-ethnic, and anti-immigrant polices that have driven Hispanics away from their party. They could change those policies, but they have chosen not to do that -- afraid it will drive many of their base voters to flee to a third party (or just stay home on election days).
Instead, they have chosen to follow other options -- sealing the border, denying citizenship to babies born of non-citizens, and suppressing the vote. Their efforts are aimed at people of Mexican heritage, who compromise the largest group of Hispanics in this country, by far (see top chart). These efforts are doomed to failure. Undocumented immigration is already at zero (which means as many are leaving as are entering). Voter suppression is having only a minimal effect. And denying citizenship to babies with non-citizen parents would require a constitutional amendment (which is very unlikely to happen).
But there is an ever bigger reason why their pitiful efforts cannot succeed, and it is illustrated in the bottom chart. About 75% of those with Mexican heritage, and 76% of all with Hispanic heritage, are citizens of this country. And most people born of Hispanic heritage in this country are born to these citizens (far more than are born to non-citizen immigrants).
To be blunt, even if the Republicans were to be successful in all their current efforts, they could not stop the demographic change that is happening. And I doubt they could even slow it down. If they don't change their policies, they are going to be a party that used to exist (like the Whigs).
These charts were made from information provided by the Pew Research Center.