While there are some members of congress who have made real efforts to attack a few of the above-mentioned problems with at least some success, none have fought hard and effectively for a broad range of progressive measures. Perhaps Dennis Kucinich has supported the broadest package of progressive measures. But his record is marred in several respects. While supporting some legislation to protect the jobs of Americans, he also supported a variety of measures to encourage immigration from poor countries, an important element in the plight of American workers. Initially a strong advocate for single-payer health insurance, he yielded to pressure exerted by the president, and voted for Obamacare. (This did not save him from being gerrymandered out of congress.)
What about Bernie Sanders, now seeking the Democratic Party nomination for the presidency? Sanders has been speaking out strongly against the growth of income inequality, has taken good positions on environmental issues, and has pledged to try to restrict the amount of money spent on election campaigns. These all concern important issues, and, in general, I agree with his positions on them.
But, regardless of how he may feel about them, he has not significantly tackled some of the most critical issues of our time. In particular, he has not been actively opposing the murderous international operations of our government, mainly in the Middle East. The "Issues" portion of his campaign website  makes no mention of the use of American drones to kill people all over the world, or of our massive military budget, or of US support of numerous unsavory national figures such as King Ibn Saud, or US support of the killing by Israel of thousands of noncombatant Israeli Arabs, including many women and children. Sanders has been actively supporting the F-35 program, and succeeded in getting funding to base many of them in Vermont. This 1-seater fighter plane is the most expensive military aircraft ever built; the cost being estimated as about $150 million each.
Regarding Snowden, Sanders said , "...there is no debate that Mr. Snowden violated an oath and committed a crime....In my view," Sanders continued, "the interests of justice would be best served if our government granted him some form of clemency or a plea agreement that would spare him a long prison sentence or permanent exile..." So Sanders thinks that the "criminal" Snowden should plea bargain and accept punishment short of a long prison sentence.
It is interesting that, while Libertarian Senator Rand Paul expressed views about Snowden similar to those of Sanders, his father, former congressman Ron Paul, also a Libertarian, expressed a rather different view of Snowden and what he did : "Edward Snowden sacrificed his livelihood, citizenship, and freedom by exposing the disturbing scope of the NSA's worldwide spying program," he said. "Thanks to one man's courageous actions, Americans know about the truly egregious ways their government is spying on them." Paul circulated a petition saying, among other things, "By signing this petition, you are telling the US government that Mr. Snowden deserves the right to come home without the fear of persecution or imprisonment." I can't find any indication of a Sanders position on any other whistle blower, such as Bradley (or Chelsea) Manning, or John Kiriakou.
While Sanders expresses real concern over the plight of American workers, and criticizes the exporting of American factories (and the associated jobs), his position on immigration is inconsistent. While sometimes expressing concern over Americans being displaced in the job market by immigrants, he advocates amnesty for the roughly eleven million illegal immigrants, and actually urges that illegal immigrants who parent children in this country be rewarded by being allowed to remain here .
Sanders seems to be trying to minimize criticism of the Obama administration. Consider the following excerpt from Sanders' campaign website:
"The good news is that the economy today is much better than when President George W. Bush left office. The bad news is that despite improvements the 40-year decline of the American middle class continues."
So, in effect, Sanders is saying that it is good that, under Obama's rule, the economy has improved, altho it is too bad that the beneficiaries of this improvement are the wealthy, while the situation is continuing to deteriorate for most people.
Two years ago, Senator Elizabeth Warren, praised Snowden,  saying, "We wouldn't even know about the NSA's spying without Edward Snowden's heroism." I have not located any more recent statements by her about Snowden. In other respects, including a pro-immigration position, her positions are very similar to Sanders', tho she is more focussed on opposition to Wall Street, and perhaps even more in accord with Obama on foreign policy and military issues.
Democrat Rush Holt, who has represented the Princeton area in the House since 1999, recently announced that he will not run again. He is arguably the most progressive member of the House, in terms of the depth and breadth of his expressed concerns. He has an excellent record on environmental issues, and on many economic issues. But, regarding Snowden, his opinion is similar to that of Sanders': Holt argues  that Edward Snowden should "face the music for breaking the law", but with "leniency" (presumably meaning a short prison sentence).
There are no modern versions of Fighting Bob La Follette in congress today.
Some people have argued that, since Sanders has taken very good positions on domestic issues such as the economy, income inequality, and human rights, we should not fault him for not making commitments on other issues such as NSA (National Security Agency) surveillance of Americans, US military interventions all over the world, and the bloated military budget. They argue that we can safely assume that, if elected president, he would deal with these matters properly. This assumption is not supported by history. There have been a number of presidents who, like Sanders, took good positions on domestic matters. but who behaved very differently with respect to foreign policy and the military.
Woodrow Wilson, a liberal on domestic matters, campaigned as a peace candidate, and then took us into World War I (during which he set precedents for civil liberties violations that still plague us). Another liberal with respect to domestic issues, Harry Truman, made the fateful decision to use the atomic bomb, and later sent our armed forces into Korea. Lyndon Johnson, very good on civil rights, greatly escalated the Vietnam War, after John Kennedy initiated our military intervention. Most people who voted for Barack Obama did not anticipate that he would wage undeclared wars in roughly a half dozen countries, or relentlessly prosecute whistleblowers, or preside over unprecedented violations of privacy in the name of national security.
Criticizing Sanders for virtual silence on important issues is not nitpicking, and does not constitute an unrealistic demand for perfection. If a candidate avoids taking clear positions on significant issues, experience indicates that, once elected, he or she will most likely deal with them badly. It also means that some important positions of the opposing candidate are unchallenged, making it likely that they will be accepted by more people.