Candidates in U.S. Senate races this year collectively raised more than a half-million dollars a day in 2013, suggesting a spate of never-ending campaign ads, mail and phone calls to come before November’s elections.

Democrats on the ballot in 2014 raised more than $108 million last year, besting Republicans’ $87 million, according to an Associated Press analysis of Senate candidates’ campaign disclosure reports filed with the secretary of the Senate and the Federal Election Commission. Incumbent Democrats outraised incumbent Republicans by more than 2-to-1 and outspent them almost 3-to-1.

Both parties’ Senate candidates started the election year with their campaign accounts totaling pretty much the same. Democratic candidates had a combined $78 million in cash; Republicans almost $80 million.

The nearly $200 million raised by candidates is slightly lower than the amount raised in 2009, when Senate candidates, both incumbents and challengers, raised almost $203 million. The 2010 Senate elections were the last time a presidential race was not on the ballots with the Senate races.

Back then, however, donors lacked the option of giving to super PACs, the outside groups that can raise unlimited cash to pay for television ads, mail and phone calls independent of a candidate’s campaign. Such groups have flourished since the Supreme Court ruled four years ago they could accept unlimited contributions from individuals.

That means candidates themselves could have less direct control over campaign money — and less money to spend — in 2014 than four years ago.

But candidates or their individual campaign committees still raise the bulk of money spent on Senate campaigns. And cash under the direct control of the candidates is more valuable because advertising rates for candidates are lower than those offered to independent groups.

The super PACs, as well as the candidates, were busy raising money in 2013. For instance, the Senate Conservatives Fund raised $7.7 million last year, while the Democrats’ Senate Majority PAC raised $8.6 million.

The party-aligned committees tasked with electing senators also have been adding cash to the mix: The Democratic Senatorial Campaign Committee raised nearly $53 million last year and the National Republican Senatorial Committee nearly $37 million.

Senators up for election in 2016 or 2018 also raised $48 million.

All told, donors and deep-pocketed candidates invested roughly a quarter-billion dollars last year in Senate contenders’ accounts. Party-controlled campaign committees and super PACs focused on the Senate set aside an additional $100 million.

Thirty-five Senate seats are up this year; Democrats will be defending 21 of them. The party breakdown in the Senate is 45 Republicans, 53 Democrats and two independents who generally vote with the Democrats. Republicans need a net gain of six seats to wrest the Senate from Democratic control.

Democratic senators already have spent heavily in defending their seats. Sen. Al Franken of Minnesota spent more than $4.6 million last year. Sen. Mark Pryor of Arkansas, one of the most vulnerable Democrats facing re-election, spent $2.8 million. And Sen. Mark Udall of Colorado spent almost $1.9 million.

Many Republican senators have to first defeat primary challenges from within the GOP before turning their attention to the general election in November.

Senate Minority Leader Mitch McConnell spent $5 million of the $8.5 million he raised last year. He faces a primary challenge from businessman Matt Bevin, who raised $1.7 million — including a $600,000 check to himself. McConnell’s likely Democratic rival, Alison Grimes, raised $4.6 million and has $3.3 million banked.

Sen. John Cornyn of Texas, who ranks just under McConnell in the GOP’s leadership, spent $3.6 million of the nearly $7.5 million he raised last year as he faces a crowded field of fellow Republicans in his primary. Of those who filed campaign finance disclosures, they reported raising less than $70,000 altogether.

Sen. Lindsey Graham, R-S.C., spent heavily to fend off tea party challengers. He spent $1.8 million last year, while his challengers combined spent one-fifth that amount.

For all the talk of insurgent candidates within the GOP, there seemed scant reason for incumbents to fear based solely on cash the candidates raised.

Incumbent Republicans facing primary challenges raised a collective $31 million and have $36 million set aside. Their expected challengers raised a collective $5.9 million and banked just shy of $2.8 million.

But the deep-pocketed outside groups could be a more potent force as the establishment wing of the GOP continues to find itself under scrutiny from rising tea party-style activists. Democrats have mostly dodged intraparty primaries.

In races where incumbents are retiring, Republican candidates raised close to $28 million for those races, while Democrats pulled in roughly $12 million.

(AP)