Recent activity in the presidential election campaign is clearly taking a toll on the images of the leading presidential candidates, as Hillary Clinton drops to her lowest net favorable rating among Democrats since Gallup began tracking her in July, and as both Ted Cruz and Donald Trump return to near their all-time lows among Republicans.

We can start with the Democratic side of the ledger, where Clinton's current net favorable rating of +36 among Democrats and Democratic-leaning independents is based on 66% who give her a favorable rating and 30% who give her an unfavorable rating.

Clinton's image has undergone ups and downs over the course of the campaign season, just as it has over her entire 25-year career in the national spotlight. Overall, however, April so far has not been kind to the former secretary of state. Her net favorable rating has descended steadily to her current low point -- in the midst of a crucial stage of the primary season, which will help determine whether she'll emerge the clear winner over Bernie Sanders before the Democratic National Convention in Philadelphia this July.

The degree of the depths to which Clinton has descended is evident when compared with her highest net favorable rating (+63, among Democrats) in early November. This means her current net favorable rating among her own partisans is about half of what it was at its peak last fall.

Sanders' image also has slid some since April 1, returning to where it was in early March. The drops in both candidates' images no doubt reflect the increasing volume of their criticism of one another. But Sanders' image remains much more positive than Clinton's -- 16 points higher on the net favorable scale.

From a long-range perspective, Sanders' image became more positive than Clinton's for the first time in January, and except for a period in the second half of February, has been above hers since. He reached his personal net favorable rating apogee (+63) in late March/early April, and although it's been down slightly since then, his is still the most positive rating for any candidate of either party at this point, by a large margin.

The big picture for Sanders is one of image improvement over time as he has become better known. This directly contrasts the big-picture trend for Clinton of a decline in her image over time, particularly in recent weeks.

Bottom line on the Democrats at this point: Sanders clearly is the better liked of the two candidates among Democrats, as Clinton's image has suffered a significant decline in recent days.

On the GOP side, it's basically a pox on both your houses when it comes to Trump and Cruz. Both are doing poorly, on an absolute basis, compared with where they were in early January and compared with the Democratic candidates. Trump currently has a +9 net favorable rating among Republicans and Republican-leaning independents, based on 52% favorable and 43% unfavorable ratings. Cruz is at +8, with 48% favorable and 40% unfavorable.

Among the three remaining Republican candidates, Cruz has suffered the biggest crash in his image. Cruz's net favorable rating among Republicans and Republican-leaning independents reached +48 at its high point in early January. From that point, it fell steadily until reaching an all-time low of +7 in early March. It recovered some later that month, but has since fallen again to +8.

Up until late February, Trump's image was always less positive than Cruz's. But since that point, the two candidates -- engaged in what can be termed direct warfare with each other -- have closely tracked one another in terms of their images. Like Cruz's, Trump's image fell in early March and has fallen again so far in April. Trump's current +9 is slightly higher than his all-time low of +5 recorded in early March.

Bottom line: Republicans perceive both Cruz and Trump in about as negative a light now as they ever have, and Republicans' ratings of the two leading candidates are way below the ratings Democrats give their candidates (even though the latter are also down).

John Kasich, meanwhile, continues with a much more positive image among Republicans than either of the other two GOP candidates. Kasich's current +26 is down from his all-time high of +35 in March, but has been edging up even as the images of Cruz and Trump have edged down.