WASHINGTON — Conservatives are increasing the pressure on Mitt Romney again.


The extended summertime silence of Mr. Romney, the Republican candidate, on his choice of a running mate has provided a new opening for social and economic conservatives to lobby for a die-hard member of their movement to join the Republican ticket.


A strongly worded Wall Street Journal editorial on Thursday urged Mr. Romney to pick Representative Paul D. Ryan of Wisconsin, the architect of the Republican budgetary vision who has pushed ambitious plans to curtail entitlement programs. The paper said Mr. Ryan “best exemplifies the nature and stakes of this election.”


The editorial follows on a fresh wave of public pressure from other conservative outlets for Mr. Romney to erase doubts about his commitment to conservative causes — an issue that has dogged Mr. Romney since his days campaigning as a liberal Republican for the Senate in Massachusetts.


The Weekly Standard on Thursday urged Mr. Romney to embrace the conservative principles in Mr. Ryan’s budget — and Mr. Ryan himself as his pick for vice president — predicting that Democrats will attack him for it anyway.


“Romney, and Republicans, will be running on the Romney-Ryan plan no matter what,” the Weekly Standard wrote. “Having Paul Ryan on the ticket may well make it easier to defend the plan convincingly.”


The not-so-subtle campaign on Mr. Ryan’s behalf may be moot if Mr. Romney has already made up his mind about a running mate, as some political observers believe. It is possible that Mr. Romney could announce his pick as early as this weekend, while on a scheduled bus tour through swing states.


The names on his short list are said to include Mr. Ryan; Senator Rob Portman of Ohio; Tim Pawlenty, the former governor of Minnesota; and perhaps Gov. Chris Christie of New Jersey.


But the loud, public calls for Mr. Ryan to emerge as the winner demonstrate again the wariness with which conservatives have always treated Mr. Romney. They suggest that there remains a desire among some conservatives for Mr. Romney to demonstrate that he is, in fact, one of them.


Mr. Romney’s campaign added to that wariness in the last couple of days on the issue of health care — a source of lingering suspicion among conservatives because Mr. Romney championed an individual mandate very similar to the one Mr. Obama pushed.


In defending Mr. Romney against an attack ad highlighting a cancer patient who had no health insurance, the campaign touted the Massachusetts health care plan, coming perilously close in the minds of some conservatives to sounding like the president.


“If people had been in Massachusetts, under Gov. Romney’s health care plan, they would have had health care,” Andrea Saul, a spokeswoman for Mr. Romney, said Tuesday. That prompted Erick Erickson, of the conservative blog, Redstate, to write on Twitter: “OMG. This might just be the moment Mitt Romney lost the election. Wow.”


But in Iowa later, Mr. Romney went out of his way to talk about his health care experience: “We’ve got to do some reforms in health care, and I have some experience doing that, as you know.”


Polls suggest that Mr. Romney’s transition from primary candidate to presumptive nominee has dramatically unified Republicans around his candidacy. Conservative support for Mr. Romney is strong, in part because of a dislike of President Obama.


But some suggest that Mr. Romney could energize conservatives and spur turnout even more by picking someone seen by the most ardent members of that group as someone who will be an uncompromising advocate for conservative principles inside a Romney White House.


The argument is about politics and about governing.


Advocates for Mr. Ryan argue that he would be a boon to Mr. Romney on the ballot by cementing in voters’ minds an economic vision for the country that is very different than Mr. Obama’s.


“The House budget chairman has defined those stakes well as a generational choice about the role of government and whether America will once again become a growth economy or sink into interest-group dominated decline,” The Journal wrote.


But the conservatives are also looking past the November election to the kind of White House they want should Mr. Romney win. For some conservatives — especially those who identify themselves with the Tea Party movement — winning is not enough.


For some of those conservatives, a Romney administration stocked with moderate Republicans is almost as bad as a second term for Mr. Obama.