Democrats in Congress have long argued that the ongoing intelligence committee investigations into Russia's interference in the presidential election and the Trump campaign's ties to the Kremlin are unlikely to get to the bottom of the issue. Now a group of "Never Trump" Republicans are planning to pressure GOP leaders to establish a bipartisan select committee to take over the inquiries and settle the matter once and for all.

Stand Up Republic, a nonprofit organization led by former independent presidential candidate Evan McMullin and his running mate, Mindy Finn, is launching a public campaign aimed at building support among Republicans for consolidating the various congressional Russia-related investigations into one empowered and fully funded select committee. The organization's ad, which goes live Tuesday with a six-figure television ad buy, makes the case that the Russia issue is too important not to investigate fully.

"Trump's Russia crisis. Secret contacts. Conflicting stories. Mounting signs of hidden ties and shady deals. Fear our president is compromised," says the narrator. "The values of liberty, justice and honor shaped America. Generations fought for freedom, and presidents of both parties stood against foreign tyrants like Vladimir Putin. Why won't Donald Trump tell Congress to name a bipartisan select committee to get the truth?"

The goal is to bring public pressure to bear on the White House and Republican congressional leadership to elevate the investigations by taking them out of the hands of the congressional intelligence committees, which don't have proper resources or support to do the job, according to McMullin. The committees are already strapped for cash, according to some leading Democrats.

"Russia's activities were a major, complex event that requires additional resources to investigate fully," said McMullin. "I simply don't believe that congressional Republican leadership are serious about investigating Russia's activities and Trump and his team's connections to Russia. Republican leaders are interested in limiting the political costs and limiting the scope and depth of these investigations."

The Senate Select Committee on Intelligence and the House Intelligence Committee are investigating Russia's hacking of political organizations, the Trump team's interactions with Russian officials and now also President Donald Trump's accusation that the Obama administration conducted surveillance on Trump and his associates at Trump Tower.

There are questions about the integrity of the congressional investigations, following revelations that the White House worked with Senate committee chairman Richard Burr, R-N.C., and House committee chairman Devin Nunes, R-Calif., asking them to contact reporters to speak on background to knock down news reports about the investigation.

Separately, the Senate Armed Services Committee is planning a series of hearings related to Russia's mischief both in the United States and around the world. Chairman John McCain, R-Ariz., has been calling for a select committee for months but has said that without the support of Republican congressional leadership, it probably won't happen.

The Senate Foreign Relations Committee has also been in touch with intelligence agencies related to the Russian interference and could hold hearings as well. Ranking Democrat Benjamin L. Cardin, Md., introduced legislation in January with other top Democrats that would establish a formal commission similar to the 9/11 Commission, to investigate all aspects of the Russia scandal.

"I don't believe any committee in Congress can conduct a thorough enough and an independent enough investigation, that's why I'm calling for a special commission," Cardin said last week.

The likelihood of a special commission being established is very low, considering that Trump would be able to veto Cardin's legislation if it ever reached his desk. A select committee doesn't need the president's approval.

Other lawmakers have called for a special counsel or a special prosecutor to take over the Russia investigation. The FBI is reportedly investigating several aspects of the case, including the Trump Organization's financial ties to Russian banks, which may or may not be related to Trump's accusations about wiretapping of Trump Tower. The FBI has never confirmed reports of its investigation.

There are several historical examples of the use of a select congressional committee to investigate a major scandal, according to the Congressional Research Service, including the Watergate Committee investigation into the Nixon administration, the Church and Pike committees' look into intelligence community abuses, the 1981 select committee inquiry into the ABSCAM scandal, and the 2005-2006 probe into the Bush administration's response to Hurricane Katrina.

But the select committee model has vulnerabilities as well, as explained by Susan Hennessey and Benjamin Wittes on the Lawfare blog last month. The chief disadvantage is that while a select committee can operate without the consent of the president, its membership is determined by congressional leaders and could become hyper-partisan, as happened with the select committee that investigated the Benghazi attacks.

"It is essential that the committee be chaired by a person whose commitment to a serious investigation is not subject to reasonable question," they wrote, suggesting Sen. Lindsey Graham, R-S.C., for the job. "And it is essential as well to populate the committee with a membership that will act in a bipartisan fashion."

The idea of a select committee is not a panacea, but if the sheer importance of determining Russia's interference in the U.S. political process and the Trump team's murky ties to Russian officials doesn't warrant such a move, it's not clear what would.