Most people don't pay much attention to politics (lucky souls), but even they "know" things about the political parties. If you love guns and lower taxes, you vote Republican. If you love abortion and open borders, vote Democrat (this list should also include if you love Social Security and Medicare and...but, well, team D is not always so good at this game). Any individual candidate might be able to prove s/he loves guns as much as Team R, but to the extent that people are voting based on party affiliations, there's really nothing to be done (and when Coke is your brand you run a big risk if too many candidates are trying to convince people that actually it tastes like Pepsi).
The rewards to trying to run to the right of conservatives on issues like immigration are... at best, zero. Much likely negative. Oh, gee, why did our base not turn out they should just know "we" are better on immigration than team R despite our policies??? If hating immigrants is your thing, it really doesn't matter how many team D deports or how "hard" their policies are. You're gonna vote Republican.
I can't find it now for some reason but someone from the UK had a thread about New Labour's (Tony Blair) approach to immigration and refugee issues, which was explicitly to run to the right of the Tories on it. And they really did run to the right on it! So much that the Tories even *sounded* more pro-refugee and pro-immigration sometimes, whatever the specific policies were. Their reward for doing this in polls was to sink like a stone among people who were anti-immigrant. The other cost of talking up an issue is that you put that issue front and center. No matter how many internment camps for immigrants it opens, Labour will still be the pro-immigrant party, and all those internment camps on the news will make people really mad about immigrants and motivate them to vote Tory. The conservative party could explicitly make "open borders" their #1 priority going into election day, and voters would still "know" who the anti-immigrant party was. If you're putting the focus on "their" issues, you're losing.
Run with your brand, don't fight it. Especially when it's the right thing on the merits.
