This week started with a new round in the attempt to undercut two seemingly ascendant, youngish Republicans who have at points in the not-so-distant past supported comprehensive immigration reform.

These men, if you let conservative Breitbart.com and the National Review tell it, are utterly suspect, possibly nefarious and certainly non-starters with the GOP base. They are, of course, Sen. Marco Rubio and newly minted House Speaker Paul Ryan -- the men The Washington Post described as the "young princes of the GOP."

Both were considered serious contenders for the vice presidential slot on the party's 2012 presidential ticket. Ryan got the nod. But when the Romney-Ryan ticket failed, the Wisconsin congressman returned to his budget work in the House. The senator from Florida, meanwhile, tried to craft and sell a comprehensive immigration reform package, which ultimately died.

Now that both men's political careers are in the midst of another moment, both have put serious work into backing away from their previous calls for immigration reform, rejecting the idea that deals can be done with Democrats in Congress and the Obama administration, and making it plain in every way that they can that they are not at all "soft" on immigration or amnesty.

By Wednesday, it seemed Rubio and Ryan were themselves in a competition to occupy the most distant post from comprehensive reform and the compromises with those on both sides of the aisle that would be required to get it done. But in their short-term pursuit of Republican support, both men might well be damaging their long-term political prospects.

First, let's consider what the two "princes" have done in recent weeks.

While Ryan was still just a prospective House speaker candidate trying to secure some promises that the Freedom Cacus would behave, Ryan's spokesman told a reporter, "We can’t address that issue [immigration] with a president we can’t trust." In the days since, Ryan — an acolyte of immigration reformers like the late Jack Kemp, the former New York congressman— has made one statement after another declaring Obama untrustworthy and immigration reform an issue not on the speaker's agenda.

He plans to dedicate his time to building an agenda and creating a collaborative process in the House in service to his first love -- the work that earned him the reputation as the Republican Party's fiscal brain. That's budget-cutting and entitlement program and social safety net reforms. On Sunday, Ryan said as much on CBS's "Face the Nation," adding a critique of Obama's immigration-related executive orders and the so-called amnesty programs created as a result.

"Look, I think it would be a ridiculous notion to try and work on an issue like this with a president we simply cannot trust on this issue," Ryan said. "He tried to go it alone, circumventing the legislative process with his executive orders, so that is not in the cards.

Meanwhile, between fending off criticism about his personal finances and use of a state Republican Party credit card for personal expenses, Rubio has also had to mount a defense against allegations from conservative media outlets and American's favorite immigration policy hard-liner, Donald Trump, that Rubio is a pro-amnesty, soft-on-immigration kind of guy. In truth, Rubio started saying that comprehensive immigration reform was a dead or null-and-void idea some time ago.

Then, on Wednesday, Rubio doubled down. With or without immigration reform in Congress, a President Rubio would end a program known as DACA that's given young undocumented adults brought to the country as children (sometimes referred to as DREAMers). So the population of illegal immigrants at daily risk of deportation would, in a Rubio administration, grow.

"This program’s now been around for three years, and we haven’t signed it by now," Rubio said. "We’re not going to extend the program. DACA is going to end. The ideal way for it to end would be it’s replaced by a reform system that creates an alternative, but if it doesn't it will end. It cannot be the permanent policy of the United States.

Bam. Problem not at all solved. The reason? Demographics and voter participation trends.

And, here again with a bit more demographic detail. Take note of which groups are participating less in presidential election years, which are voting more and and when each began.

So many of the expectations about Ryan's political future and even his rise to the speaker role is built on the idea that he is a young, bright, bold Republican with an incredible command of the details of the federal budget -- and yet also that he is firmly ensconced in the mainline, establishment wing of the party.

He wants and has voted for a legitimately conservative fiscal and social agenda, but he isn't a Republican who calls for Obama's impeachment each time word reaches Capitol Hill that someone removed a pencil from the Oval Office. He's the kind of Republican with which Democrats often do not agree, but have and can find a way to work with. He can appeal to (or at least not repulse) tea party lawmakers, as well as voters in both parties. He also can get the support of the business lobby, evangelicals and likely the relatively small shares of black, Latino and Asian voters who already back Republicans. (The Romney-Ryan ticket is the only losing political bid he's ever made.) And that entire coalition and his ability to expand it will determine the success or failure of any future political career leaps Ryan might want to make.

But all of that is also at real risk if Speaker Ryan becomes a leader committed to blocking immigration reform or someone who can't stop talking about Obama as a political enemy and immigration reform as an unimportant or futile cause.

Rubio's shining-star status in the Republican Party is all about his inspirational, this-is-what's-possible-in-America story. Yes, his tenure as a state lawmaker and his oratorical skills and fluency in both English and Spanish also likely matter. But it's also the fact that he's the son of a Cuban-immigrant bartender with significant student loan debt and financial challenges -- the bootstraps nature of his political rise.

It's helped him do well with big-money donors and secure a lot of support from the country club and retirement village sets that are also part of the Republican base. And as Rubio's biggest boosters often brag and his political enemies often seem to fear, Latino voters across the political spectrum might be willing to consider him even vote for him if he's the presidential nominee.

But as with Ryan, the possibility of the building that bigger, broader coalition of support shrinks markedly if he too becomes more of an immigration hard-liner.

For Rubio, there's also the added weight of being a Cuban American who opposes immigration reforms and executive actions that would be of large benefit to Latinos of Mexican and Mexican American origin. That is only likely to draw added attention to the fact that while Cuban immigrants have at least one risky illegal immigration option that leads to citizenship, Mexican immigrants do not. And Latinos of Mexican origin comprise the majority of the American Latino electorate.

(It's also worth noting DREAMers and other young, immigration-focused activists are now very experienced mobilizing eligible Latino voters to participate politically with the interest of those who cannot vote in mind.)

To be clear, immigration is far from the only issue that matters to fast-growing shares of the American electorate such as Latinos. But it does matter a lot. And long term, becoming an immigration hard-liner is just the sort of thing that can earn either of the young princes some political enemies.